I can confirm that for the past few weeks I've had the same issue of ANY
player on my team
that has staff attributes (ie can be offered staff role) shows in the "Staff List" with a job role as player and they do not show in the "Player List" when I filter by squad.
If I search for the player manually in returns the player in the player list. But when filtering by squad only shows the player in the staff list.
I've taken some screenshot to show this:
Player search for Maguire
Filtered by squad Player List
Filtered by squad Staff List
@Stam hope this shows the issue a bit clearer now