Functions: WordPress upload_mimes does not work for front-end loads of 3D files

Then, after the new WP updates, my form will not allow certain files to be uploaded. I have a Gravity form with a loading field to send 3D printing files. I can make one type of file work, but not the others. I just hope that someone else has had this problem and has some update on a solution.

I'm using:

add_filter (& # 39; upload_mimes & # 39 ;, & # 39; add_custom_mime_types & # 39 ;, 1,1);
add_custom_mime_types ($ mime_types) {function
$ mime_types['stl'] = & # 39; application / wavefront-stl & # 39 ;;
$ mime_types['igs'] = & # 39; application / iges & # 39 ;;
$ mime_types['stp'] = & # 39; application / step & # 39 ;;
$ mime_types['step'] = & # 39; application / step & # 39 ;;

returns $ mime_types;
}

Interestingly, the .stl will rise but not the others. I have also installed the Extra File Types add-on to add file types, but there is no help there. Deactivating Real MIME Check did not work either.

I also added:

define (& # 39; ALLOW_UNFILTERED_UPLOADS & # 39 ;, true);

to wp-config and I can upload these files to the media library as an administrator, but I need them to load from my front-end form.