Unable to assign role to a new member

I am writing only about the FTH website. We use the member management section in the admin console to add members, they opt in, and then it becomes possible to assign roles on agendas.

In particular, the member's name switched from being listed in [strike]strikethrough style[/strike] format to normal format (switch happened yesterday or the day before). We have contacted the member and asked them to opt in again.