Cannot select casting options
Playing on PC, there appears to be a bug which appears any time you are given an option during casting (for example, when choosing whether or not to cast the back side of a battle or choosing to cast the Adventure of a card with an Adventure). Any time the popup comes up, the game slows to a crawl with some sort of animation appearing above the selectable options, however clicking the options does not appear to do anything. Selecting "decline" or "cancel" similarly has no effect. Toggling back to the battlefield from the browser removes any stutter or strange animations, but returning to the browser resumes them - and occasionally also erases options from view.
The only way to leave the screen seems to be running out of time. However, the most recent time that this happened, when time expired, not only was my turn passed with no game actions, but the card that I had been attempting to play had disappeared from all zones.