@wp85: it's not a bug. The table master has to re-open the table by pressing X to include you in the game.
The reason for this is the scoring: the scoring would be inconsist if there was players always going in and out of the game. Especially in uno, because you could go out and in again and say hey, I'm the best, I have 0 points...
A second reason is because some games requires exactly a fixed number of players. For example, many cards games can only be played with 4 players. IN that configuration, it is logically not possible to join and leave during a game splitted in multiple rounds.
As third and last reason, I would also justify that by saying that the poker game behave like a tournament, not as a cash game: you have a finite stack at the beginning, and it would be unfair for next to bankrupted players to have a new one entering with full stack in the middle of a game.
All these reasons don't have sens for all games, that's true. But to make things simple and behaving the same everywhere, I decided so.