"User has been removed"

I am seeing an issue within my app where a user's name shows becomes italicized and says "User has been removed" once a form is saved.

The use case is a group approval form. In section 1 you enter names from different groups as approvers, and then they can select their approval decision from a multiple choice dropdown in section 2. 

For some users, once the are selected as approvers in section 1 and the form is saved, their name becomes italicized and says "User has been removed". I have verified that this person is active in the app's user list. 

Has anyone else seen this behavior and if so how was it resolved?