I just played a BO3 game against "Mike". After the end of the first game, the client never showed me the sideboard as it should. Instead, it kept showing me the battlefield as it was at the end of the game. It was just stuck there for more than 10 seconds.

The gear icon in the corner and other UI elements were also taken away, so I couldn't quit out or do anything. The only button that looked enabled was the "skip to end of turn" button, but clicking it does nothing.

I manually alt-tabbed out of the game, killed it, and restarted. When it came back up it went to "Finding existing matches", and then I got the Phyrexian text description instead of one of the normal ones. It sat there for over a minute. At one point the bottom text moved to "Waiting for opponent". Eventually, after waiting long enough (until sideboarding time ran out?), it started up the second game.

I never got a chance to sideboard and the client was obviously broken. I've attached the game log so you can look. Please fix this because I can remember it happening multiple times.