Hello,
Testing setup: two custom groups.
1st: Proved_Members / Title: Proved Member – not a autom. primary group
2nd: Team_Members / Title: Team Member – a autom. primary group
Group-Owner is a admin user, now you’re adding you real user (not the admin) to the first group and the user has “Proved Member” as title. Now you’re adding this user to your 2nd group also, but the user has still the old title. Okay, now you’re deleting the first group from your testing patient, and his title is still from the first group. You has to delete the title manually. 
It’s confusing me 
Best regards