Are you using an antivirus program on your Moodle server that might be affecting students and not teachers?
Thanks for replying.
We did turn off ClamAV and that did not fix the issue.
The problem ended up being that we never converted the InnoDB tables to Barracuda. Here is the article talking about how to fix the table conversion.
https://docs.moodle.org/32/en/Administration_via_command_line It is about half way down the page. After updating the tables assignments upload almost instantly.