To be honest, I haven’t got a clue, so this is just a guess. You could try removing the $post_id query argument in your pre_save_post filter.
I don’t think that resetting the form before it is submitted is a good idea, which is what I’m assuming that the JS code above is doing. Wouldn’t that cause default values to be sent in the submission of the form? More than likely that code is never happening or you’d see other problems. You might be able to reset the form on the acf/ready JS action https://www.advancedcustomfields.com/resources/adding-custom-javascript-fields/, but I’m not sure.
