[2.0.x] fix home endstop bug (DON'T MERGE, needs discussion) (#11900)

Marlin/src/module/endstops.cpp

     run_monitor();  // report changes in endstop status
   #endif
 
-  #if ENABLED(ENDSTOP_INTERRUPTS_FEATURE) && ENABLED(ENDSTOP_NOISE_FILTER)
-    if (endstop_poll_count) update();
-  #elif DISABLED(ENDSTOP_INTERRUPTS_FEATURE) || ENABLED(ENDSTOP_NOISE_FILTER)
+  #if DISABLED(ENDSTOP_INTERRUPTS_FEATURE)
     update();
+  #elif ENABLED(ENDSTOP_NOISE_FILTER)
+    if (endstop_poll_count) update();
   #endif
 }
 
   enabled = enabled_globally;
 
   #if ENABLED(ENDSTOP_INTERRUPTS_FEATURE)
-    update();
+    // Still 'enabled'? Then endstops are always on and kept in sync.
+    // Otherwise reset 'live's variables to let axes move in both directions.
+    if (!enabled) {
+      #if ENABLED(ENDSTOP_NOISE_FILTER)
+        endstop_poll_count = validated_live_state = 0; // Stop filtering
+      #endif
+      live_state = 0;
+    }
+  //#else
+    // When in polling endstops are always kept in sync
   #endif
 }
 
     if (triple_hit) { \
       _ENDSTOP_HIT(AXIS1, MINMAX); \
       /* if not performing home or if both endstops were trigged during homing... */ \
-      if (!stepper.separate_multi_axis || triple_hit == 0x7) \
+      if (!stepper.separate_multi_axis || triple_hit == 0b111) \
         planner.endstop_triggered(_AXIS(AXIS1)); \
     } \
   }while(0)

Marlin/src/module/endstops.h

 
   public:
 
-    static bool enabled, enabled_globally;
-
     #if ENABLED(X_DUAL_ENDSTOPS) || ENABLED(Y_DUAL_ENDSTOPS) || Z_MULTI_ENDSTOPS
       typedef uint16_t esbits_t;
       #if ENABLED(X_DUAL_ENDSTOPS)
     #endif
 
   private:
+    static bool enabled, enabled_globally;
     static esbits_t live_state;
     static volatile uint8_t hit_state;      // Use X_MIN, Y_MIN, Z_MIN and Z_MIN_PROBE as BIT index