I have also tested that, it didn’t work too.
I think there is a problem with sending the form. When I add the documents to the field it still works, the error occurs only by sending the form.
When I change the upload size to 5MB and try to add a pdf with 8 MB, then I directly get the message that the document is too big.
But in my case I only get the error message when try to submit the form.