I remember discussing this quite a while ago with someone else. It looks like there's a possibility that certain NPCs vanish after a certain point in the playthrough and there are a couple of others that can bug out so that their "Play Gwent?" dialogues don't appear. I'm not sure if it was ever determined exactly how / why / when it happens...and it doesn't seem to happen for everyone.
Did you begin this playthrough under v1.31?
Did you begin this playthrough under v1.31?