Samba Users access denied with an @ in username but can connect without @

I have a Debian 9 server that I just installed along with Samba to do a file sharing service to Windows and linux devices on the network.

I created some users as well as samba users along with a testing share.

The issue I’ve found is that when I have an @ sign in the samba username, the testing share comes back with “access denied”. If I don’t have an @ sign then the testing share works.

Really confused because I’m migrating this away from an Ubuntu setup where I used email addresses as the usernames and it worked just fine but on Debian 9 it doesn’t.

I checked the logs in /var/log/samba/ folder and didn’t see any response as to why the full email address user showed access denied but that same user without the @. would work (I did setup both accounts using the same commands).

Any ideas?