fixed the st_synchronize. it would have continued if there is only the last move of the buffer being stepped.

Marlin/planner.h

@@ -130,4 +130,14 @@ FORCE_INLINE block_t *plan_get_current_block()
   block->busy = true;
   return(block);
 }
+
+// Gets the current block. Returns NULL if buffer empty
+FORCE_INLINE bool blocks_queued() 
+{
+  if (block_buffer_head == block_buffer_tail) { 
+    return false; 
+  }
+  else
+    return true;
+}
 #endif

Marlin/stepper.cpp

@@ -706,21 +706,16 @@ void st_init()
   sei();
 }
 
-#define TEMPORARY_Z_HOME_SOUND_FIX
-#ifdef TEMPORARY_Z_HOME_SOUND_FIX
+
 #include <util/delay.h>
-#endif
 // Block until all buffered steps are executed
 void st_synchronize()
 {
-  while(plan_get_current_block()) {
+  while(current_block!=0 || blocks_queued()) {
     manage_heater();
     manage_inactivity(1);
     LCD_STATUS;
-    #ifdef TEMPORARY_Z_HOME_SOUND_FIX
-    _delay_ms(200);
-    _delay_ms(200);
-    #endif
+    //_delay_ms(1);
   }
 }