I had the exact same thing happen to me. I used Scattered thoughts, I had selected 1 card (Sorin the Mirthless) and before choosing my 2nd I wanted to look in my graveyard first and when I returned it was locked on 1 selection and it wouldn't allow me to select/deselect anything or resolve the card. Inevitably the game timed out and I got no use out of it. Was fortunate to somehow still win, but this bug is still very problematic.
I had the exact same thing happen to me. I used Scattered thoughts, I had selected 1 card (Sorin the Mirthless) and before choosing my 2nd I wanted to look in my graveyard first and when I returned it was locked on 1 selection and it wouldn't allow me to select/deselect anything or resolve the card. Inevitably the game timed out and I got no use out of it. Was fortunate to somehow still win, but this bug is still very problematic.