How do I resolve Apple's claim of an MDM on my personal iPhone to trade it in?

Apple Store reps claim apple's records show that an mdm is on my personal phone. I have checked on the phone and do not see an mdm in the vpn & device window. I have a separate work phone and checked and work has no record of installing an mdm on that phone but of course do have a record relating to my work phone. I also checked with my cell carrier and they do not show any mdm associated with my phone.

I want to trade this phone in to get a new phone, but of course apple is saying I have to take the mdm off first.

Anyone encounter this, and if they were able to solve the issue how did they do it?

The only thing I can think of doing is going back to the store and showing the new rep the phone does not indicate any MDM on it, and telling them apple has their records wrong. Ugg.

Thanks!

[Re-Titled by Moderator]