I have same problem,
in Squad menu, my GK disappear, 11 field players
in Preview window, I have 12 players
in Match, my newest signed up player auto kicked out (disappear for whole match, not even in the bench) to get spot for GK (I thank God for this ) <- cost me a lot to figure this

Try everything to fix this, log out, clear cache, clear data, .. nothing fixed. I guess the error is on server side.
Reported with screenshot to in-game Support over 24h ago, no response yet.