The reason is the removal of this function in assets/js/acf-input.js
get_field_key: function( $field ){
return this.get_data( $field, 'key' );
},
Is third party plugins supposed to depend on this function?
Anyways it might be worthwhile to keep it to retain compatibility.
We did not expect this to break in a minor update
I had this exact problems, I had a backup ready, but its still a mess to sort out. Why have not this problem been adressed since september?
Best regards Andreas