When you disconnect during your turn, the timer goes on Pause. When you disconnect on your opponent's turn, and it ends, your timer will expire during your disconnection. This is most problematics when you have to restart the client for any reason.
We have tested disconnections extensively recently and we have not seen any real issues with disconnections. The case you describe, during the test, is only a visual problem for the player who is still connected, and if you reconnect, you still have the correct time. Of course, any time you actually lost during the time the game had not yet concluded you were disconnected, would not be restored.
I recognize this since I saw it as the connected user. Anyway a few weeks ago I had to reconnect for some lag issues and I remember having my turn complety wasted once I've entered the match. May it be that the timer starts running once you are connected to the client rather than to the match itself?
We tested this specific case as well and was not able to find anything. Given our investigations, I mostly suspect that much of the disconnect issues we hear about is largely just "recognition lag" where there is a delay between when you actually disconnected and when the game knows that you are disconnected. Unfortunately, this is mostly due to the way internet connections work and is unlikely to be improved by anything we do. (Just another thing where turn-based/timer-based stuff makes things more difficult, compared to a real-time game.)
To add some input on this, I just lost 40 seconds from instantly quitting and rejoining. Like the whole process the server didn't knew I was off...
