Files do not upload when running a collection / folder

Hello Everyone! I need your help with my issue:

I wrote a bunch of REST API tests that required file upload. When sending request to the endpoints separately it works perfectly.
However when I want to run the folder or the whole collection, all the data uploads fail. Request Body is “{}” which to me indicates it could not find the files that were supposed to be sent.
These files are small pictures and pdfs, totaling less than a Mb.

Thanks in advance!