Hi @askelly ,
You’ve done the right thing of going into the File object’s settings and restricting the file types from there, that is how files types are restricted.
However, when you save the form where you’re uploading a restricted file, you should receive either a validation error stating the file is not allowed, or a banner message to state your file hasn’t been uploaded.
As you’re not receiving either, I would raise a Support Ticket for this.
Hope this helps 