Disc unreadable when loading Zer0 in couch co-op

A friend and I have been running through BL2 couch co-op, Zer0 and Krieg respectively, and whenever his Zer0 (lvl 63) character loads up, there is a brief second between actually selecting the storage device to the error message of “disc not readable”.
I narrowed down all possibilities as to why this is happening and I know it has something to do with this specific character loading up but I can’t pinpoint the issue. On two separate occasions I was able to play for roughly 5 mins as his character, but solo. I unequipped all his gear, respec’d and used all Badass tokens, nothing helped. Game works fine when I load up his Gaige or Maya, but not his Zer0. Even deleted and reinstalled all DLC and patches, but to no avail.
Nothing has helped and we just want to cap out at least one character before we make another serious character or make the jump to pre-sequel. If anyone has faced an issue exactly or similar to this, please refer me whatever fix you used, thank you!