Also call clear_command_queue for lcd_sdcard_stop

Marlin/Marlin.h

 bool enqueue_and_echo_command(const char* cmd, bool say_ok=false); //put a single ASCII command at the end of the current buffer or return false when it is full
 void enqueue_and_echo_command_now(const char* cmd); // enqueue now, only return when the command has been enqueued
 void enqueue_and_echo_commands_P(const char* cmd); //put one or many ASCII commands at the end of the current buffer, read from flash
+void clear_command_queue();
 
 void clamp_to_software_endstops(float target[3]);
 

Marlin/Marlin_main.cpp

   drain_queued_commands_P(); // first command executed asap (when possible)
 }
 
+void clear_command_queue() {
+  cmd_queue_index_r = cmd_queue_index_w;
+  commands_in_queue = 0;
+}
+
 /**
  * Once a new command is in the ring buffer, call this to commit it
  */

Marlin/ultralcd.cpp

   static void lcd_sdcard_stop() {
     stepper.quick_stop();
     set_current_position_from_planner();
+    clear_command_queue();
     card.sdprinting = false;
     card.closefile();
     print_job_timer.stop();