diff --git a/Marlin/Marlin_main.cpp b/Marlin/Marlin_main.cpp
index 9a2ab20cdb42fea379c5d710dfc8e209a4357af6..e5dcc5fea0cfaa09f3b81145997c66e7e3413865 100644
--- a/Marlin/Marlin_main.cpp
+++ b/Marlin/Marlin_main.cpp
@@ -4360,7 +4360,7 @@ void home_all_axes() { gcode_G28(); }
 
       verbose_level = code_seen('V') && code_has_value() ? code_value_int() : 0;
       if (!WITHIN(verbose_level, 0, 4)) {
-        SERIAL_PROTOCOLLNPGM("?(V)erbose Level is implausible (0-4).");
+        SERIAL_PROTOCOLLNPGM("?(V)erbose level is implausible (0-4).");
         return;
       }
 
@@ -5081,7 +5081,7 @@ void home_all_axes() { gcode_G28(); }
 
       const int8_t verbose_level = code_seen('V') ? code_value_byte() : 1;
       if (!WITHIN(verbose_level, 0, 2)) {
-        SERIAL_PROTOCOLLNPGM("?(V)erbose Level is implausible (0-2).");
+        SERIAL_PROTOCOLLNPGM("?(V)erbose level is implausible (0-2).");
         return;
       }
 
@@ -6183,7 +6183,7 @@ inline void gcode_M42() {
 
     const int8_t verbose_level = code_seen('V') ? code_value_byte() : 1;
     if (!WITHIN(verbose_level, 0, 4)) {
-      SERIAL_PROTOCOLLNPGM("?Verbose Level not plausible (0-4).");
+      SERIAL_PROTOCOLLNPGM("?(V)erbose level is implausible (0-4).");
       return;
     }
 
diff --git a/Marlin/least_squares_fit.cpp b/Marlin/least_squares_fit.cpp
index 59a23ca4a5a8f9ca4d98f3f5914a889634de5961..271aae11ffd89dc1127717783bcacb0cdb0e22da 100644
--- a/Marlin/least_squares_fit.cpp
+++ b/Marlin/least_squares_fit.cpp
@@ -73,8 +73,9 @@ int finish_incremental_LSF(struct linear_fit_data *lsf) {
   lsf->yzbar = lsf->yzbar / N - lsf->ybar * lsf->zbar;
   lsf->xzbar = lsf->xzbar / N - lsf->xbar * lsf->zbar;
   const float DD = lsf->x2bar * lsf->y2bar - sq(lsf->xybar);
+
   if (fabs(DD) <= 1e-10 * (lsf->max_absx + lsf->max_absy))
-    return -1;
+    return 1;
 
   lsf->A = (lsf->yzbar * lsf->xybar - lsf->xzbar * lsf->y2bar) / DD;
   lsf->B = (lsf->xzbar * lsf->xybar - lsf->yzbar * lsf->x2bar) / DD;
diff --git a/Marlin/ubl.cpp b/Marlin/ubl.cpp
old mode 100755
new mode 100644
index aa1fc88739d0fa103d30badfd4aec570e1702480..5471b178e2ea12bb3c71f2a0d5d22f9296238e62
--- a/Marlin/ubl.cpp
+++ b/Marlin/ubl.cpp
@@ -50,13 +50,6 @@
     safe_delay(10);
   }
 
-  static void serial_echo_mspaces(const uint8_t cnt) {
-    for (uint8_t i = GRID_MAX_POINTS_X - 1; --i;) {
-      SERIAL_ECHO_SP((uint8_t)cnt);
-      safe_delay(10);
-    }
-  }
-
   ubl_state unified_bed_leveling::state;
 
   float unified_bed_leveling::z_values[GRID_MAX_POINTS_X][GRID_MAX_POINTS_Y],
@@ -148,12 +141,11 @@
     if (map0) {
       SERIAL_PROTOCOLLNPGM("\nBed Topography Report:\n");
       serial_echo_xy(0, GRID_MAX_POINTS_Y - 1);
-      SERIAL_ECHO_SP(3);
-      serial_echo_mspaces(spaces);
+      SERIAL_ECHO_SP(spaces * (GRID_MAX_POINTS_X - 2) + 3);
       serial_echo_xy(GRID_MAX_POINTS_X - 1, GRID_MAX_POINTS_Y - 1);
       SERIAL_EOL;
       serial_echo_xy(UBL_MESH_MIN_X, UBL_MESH_MAX_Y);
-      serial_echo_mspaces(spaces);
+      SERIAL_ECHO_SP(spaces * (GRID_MAX_POINTS_X - 2));
       serial_echo_xy(UBL_MESH_MAX_X, UBL_MESH_MAX_Y);
       SERIAL_EOL;
     }
@@ -198,13 +190,11 @@
 
     if (map0) {
       serial_echo_xy(UBL_MESH_MIN_X, UBL_MESH_MIN_Y);
-      SERIAL_ECHO_SP(4);
-      serial_echo_mspaces(spaces);
+      SERIAL_ECHO_SP(spaces * (GRID_MAX_POINTS_X - 2) + 4);
       serial_echo_xy(UBL_MESH_MAX_X, UBL_MESH_MIN_Y);
       SERIAL_EOL;
       serial_echo_xy(0, 0);
-      SERIAL_ECHO_SP(5);
-      serial_echo_mspaces(spaces);
+      SERIAL_ECHO_SP(spaces * (GRID_MAX_POINTS_X - 2) + 5);
       serial_echo_xy(GRID_MAX_POINTS_X - 1, 0);
       SERIAL_EOL;
     }
diff --git a/Marlin/ubl_G29.cpp b/Marlin/ubl_G29.cpp
index b26096a9719ed8534a92ade982e5202f2b764c06..326f39d1647df3c6a89cce50e206723ed17d3d0d 100644
--- a/Marlin/ubl_G29.cpp
+++ b/Marlin/ubl_G29.cpp
@@ -311,17 +311,16 @@
   #define USE_PROBE_AS_REFERENCE 1
 
   // The simple parameter flags and values are 'static' so parameter parsing can be in a support routine.
-  static int g29_verbose_level, phase_value = -1, repetition_cnt,
+  static int g29_verbose_level, phase_value, repetition_cnt,
              storage_slot = 0, map_type, grid_size;
   static bool repeat_flag, c_flag, x_flag, y_flag;
   static float x_pos, y_pos, measured_z, card_thickness = 0.0, ubl_constant = 0.0;
 
-    extern void lcd_setstatus(const char* message, const bool persist);
-    extern void lcd_setstatuspgm(const char* message, const uint8_t level);
+  extern void lcd_setstatus(const char* message, const bool persist);
+  extern void lcd_setstatuspgm(const char* message, const uint8_t level);
 
   void __attribute__((optimize("O0"))) gcode_G29() {
 
-
     if (ubl.eeprom_start < 0) {
       SERIAL_PROTOCOLLNPGM("?You need to enable your EEPROM and initialize it");
       SERIAL_PROTOCOLLNPGM("with M502, M500, M501 in that order.\n");
@@ -384,21 +383,17 @@
     }
 
     if (code_seen('J')) {
-      if (!WITHIN(grid_size, 2, 9)) {
-        SERIAL_PROTOCOLLNPGM("ERROR - grid size must be between 2 and 9");
-        return;
-      }
       ubl.save_ubl_active_state_and_disable();
       ubl.tilt_mesh_based_on_probed_grid(code_seen('O') || code_seen('M'));
       ubl.restore_ubl_active_state_and_leave();
     }
 
     if (code_seen('P')) {
-      phase_value = code_value_int();
-      if (!WITHIN(phase_value, 0, 7)) {
-        SERIAL_PROTOCOLLNPGM("Invalid Phase value. (0-4)\n");
-        return;
+      if (WITHIN(phase_value,0,1) && ubl.state.eeprom_storage_slot==-1) {
+        ubl.state.eeprom_storage_slot=0;
+        SERIAL_PROTOCOLLNPGM("Default storage slot 0 selected.\n");
       }
+
       switch (phase_value) {
         case 0:
           //
@@ -420,7 +415,7 @@
             SERIAL_PROTOCOLPAIR("Probing Mesh Points Closest to (", x_pos);
             SERIAL_PROTOCOLCHAR(',');
             SERIAL_PROTOCOL(y_pos);
-            SERIAL_PROTOCOLLNPGM(")\n");
+            SERIAL_PROTOCOLLNPGM(").\n");
           }
           ubl.probe_entire_mesh(x_pos + X_PROBE_OFFSET_FROM_EXTRUDER, y_pos + Y_PROBE_OFFSET_FROM_EXTRUDER,
                             code_seen('O') || code_seen('M'), code_seen('E'), code_seen('U'));
@@ -460,7 +455,7 @@
             }
           }
           manually_probe_remaining_mesh(x_pos, y_pos, height, card_thickness, code_seen('O') || code_seen('M'));
-          SERIAL_PROTOCOLLNPGM("G29 P2 finished");
+          SERIAL_PROTOCOLLNPGM("G29 P2 finished.");
 
         } break;
 
@@ -757,8 +752,6 @@
   }
 
   void unified_bed_leveling::tilt_mesh_based_on_3pts(const float &z1, const float &z2, const float &z3) {
-    int i, j;
-
     matrix_3x3 rotation;
     vector_3 v1 = vector_3( (UBL_PROBE_PT_1_X - UBL_PROBE_PT_2_X),
                             (UBL_PROBE_PT_1_Y - UBL_PROBE_PT_2_Y),
@@ -892,14 +885,14 @@
       //, min(planner.max_feedrate_mm_s[X_AXIS], planner.max_feedrate_mm_s[Y_AXIS]) / 2.0);
 
     stepper.synchronize();
-    SERIAL_PROTOCOLPGM("Place shim under nozzle");
+    SERIAL_PROTOCOLPGM("Place shim under nozzle.");
     say_and_take_a_measurement();
 
     const float z1 = use_encoder_wheel_to_measure_point();
     do_blocking_move_to_z(current_position[Z_AXIS] + SIZE_OF_LITTLE_RAISE);
     stepper.synchronize();
 
-    SERIAL_PROTOCOLPGM("Remove shim");
+    SERIAL_PROTOCOLPGM("Remove shim.");
     say_and_take_a_measurement();
 
     const float z2 = use_encoder_wheel_to_measure_point();
@@ -1039,14 +1032,22 @@
 
     g29_verbose_level = code_seen('V') ? code_value_int() : 0;
     if (!WITHIN(g29_verbose_level, 0, 4)) {
-      SERIAL_PROTOCOLLNPGM("?(V)erbose Level is implausible (0-4)\n");
+      SERIAL_PROTOCOLLNPGM("?(V)erbose level is implausible (0-4).\n");
       err_flag = true;
     }
 
+    if (code_seen('P')) {
+      phase_value = code_value_int();
+      if (!WITHIN(phase_value, 0, 6)) {
+        SERIAL_PROTOCOLLNPGM("?(P)hase value invalid (0-6).\n");
+        err_flag = true;
+      }
+    }
+
     if (code_seen('J')) {
       grid_size = code_has_value() ? code_value_int() : 3;
-      if (!WITHIN(grid_size, 2, 5)) {
-        SERIAL_PROTOCOLLNPGM("Invalid grid probe points specified.\n");
+      if (!WITHIN(grid_size, 2, 9)) {
+        SERIAL_PROTOCOLLNPGM("?Invalid grid size (J) specified (2-9).\n");
         err_flag = true;
       }
     }
@@ -1607,7 +1608,10 @@
       zig_zag ^= true;
     }
 
-    const int status = finish_incremental_LSF(&lsf_results);
+    if (finish_incremental_LSF(&lsf_results)) {
+      SERIAL_ECHOPGM("Could not complete LSF!");
+      return;
+    }
 
     if (g29_verbose_level > 3) {
       SERIAL_ECHOPGM("LSF Results A=");