More logging of matrix behavior

Marlin/Marlin_main.cpp

     #if DISABLED(DELTA)
 
       static void set_bed_level_equation_lsq(double* plane_equation_coefficients) {
+
         #if ENABLED(DEBUG_LEVELING_FEATURE)
-          if (DEBUGGING(LEVELING)) DEBUG_POS("BEFORE set_bed_level_equation_lsq", current_position);
+          plan_bed_level_matrix.set_to_identity();
+          if (DEBUGGING(LEVELING)) {
+            vector_3 uncorrected_position = plan_get_position();
+            DEBUG_POS(">>> set_bed_level_equation_lsq", uncorrected_position);
+            DEBUG_POS(">>> set_bed_level_equation_lsq", current_position);
+          }
         #endif
 
         vector_3 planeNormal = vector_3(-plane_equation_coefficients[0], -plane_equation_coefficients[1], 1);
         current_position[Z_AXIS] = corrected_position.z;
 
         #if ENABLED(DEBUG_LEVELING_FEATURE)
-          if (DEBUGGING(LEVELING)) DEBUG_POS("AFTER set_bed_level_equation_lsq", current_position);
+          if (DEBUGGING(LEVELING)) DEBUG_POS("<<< set_bed_level_equation_lsq", current_position);
         #endif
 
         sync_plan_position();
       #else //!DELTA
 
         #if ENABLED(DEBUG_LEVELING_FEATURE)
-          if (DEBUGGING(LEVELING)) DEBUG_POS("BEFORE matrix.set_to_identity", current_position);
+          if (DEBUGGING(LEVELING)) {
+            vector_3 corrected_position = plan_get_position();
+            DEBUG_POS("BEFORE matrix.set_to_identity", corrected_position);
+            DEBUG_POS("BEFORE matrix.set_to_identity", current_position);
+          }
         #endif
 
         //vector_3 corrected_position = plan_get_position();
         current_position[Z_AXIS] = uncorrected_position.z;
 
         #if ENABLED(DEBUG_LEVELING_FEATURE)
-          if (DEBUGGING(LEVELING)) DEBUG_POS("AFTER matrix.set_to_identity", current_position);
+          if (DEBUGGING(LEVELING)) DEBUG_POS("AFTER matrix.set_to_identity", uncorrected_position);
         #endif
 
         sync_plan_position();