Unfortunately, unless we can reproduce it on our end, we can’t diagnose or fix it. However, we can make sure that the reconnect works. When this happens, ALT+F4 and rejoin the game, it should reconnect and the duel should continue.
Likely the game gave victory to your opponent if you ran out of time or if you disconnected during the side deck screen.
I can see from the screenshot that you have a face-down monster in atk position. This does mean that the reconnect didn’t work, so we’ll test this. That is something we can likely reproduce and fix.