last week I installed the newest Version of Nintex Forms, since then my user have the problem that they can't upload files as attachments that are stored on our network drives in several folders. They become the error message "The specified file or folder name is too long. It should not be more than 128 characters". But only if we use Nintex Forms on the list! For tests I deleted the Nintex Forms on the list and the upload is working again. If I copy the files to the desktop and upload it, it works.
I already wrote to the support, but maybe someone here can help me too
I think that they are having some trouble with that particular update. In a different thread, someone else has mentioned that they seem to be working on a hotfix for a few issues (https://community.nintex.com/thread/21116-repeating-section-rows-resizing-with-hidden-controls#comme...).
Sounds like you've already contacted support though, so hopefully they can roll in whatever is happening for your case into whatever they are making to fix the problems that have been discovered thus far.