Past employee still shows up?

This is a weird one, so bare with me please.

We have a current & past employee with the same first name, working for us at different times. We assign all of our employees email addresses and these 2 were given the same email address. Because of the gap in employment between the 2, we figured there wouldn't be an issue, until now. We even deleted the old email address from our system and assigned a new one to the current employee. When I share a sheet with the current employee, it always wants to revert back to the past employees profile & email address. (Even though I'm typing in the new correct address) I've deleted the past employee email address from all sheets & profiles thinking this would solve the issue. It hasn't.

It's very frustrating