Contract expired probably at some time when I played a friendly (the player didn't play at all), and he's still at a club
Maybe I should just release him (I wanted to see if he'll join inactive team when his contract expires, like when a player is released)

J. Carbià

I've just released him, so the topic can be closed, though it looks like a bug, but probably not that important (I don't think many allow player's contract to run out, especially not intentionally)