Merge pull request #7560 from thinkyhead/bf1_m406_patch

Addressing #7552

Marlin/Marlin_main.cpp

@@ -9241,7 +9241,10 @@ inline void gcode_M400() { stepper.synchronize(); }
   /**
    * M406: Turn off filament sensor for control
    */
-  inline void gcode_M406() { filament_sensor = false; }
+  inline void gcode_M406() {
+    filament_sensor = false;
+    calculate_volumetric_multipliers();   // Restore correct 'volumetric_multiplier' value
+  }
 
   /**
    * M407: Get measured filament diameter on serial output