Can't Follow Friend's Item Filter

I used to follow a friend's item filter in a previous league and can't seem to follow it in this one. Typically, there's a follow button by the filter they link to me. However, in this league I can only pick copy instead of follow. We've gone through their profile settings to try and figure it out but nothing fixes it.

Does anyone know how to fix this?

Bump

Solution for anyone else with this issue: There's a cap on how many item filters you can follow. Unfollow some filters and you should be able to follow your friend's filter again.