My opponent used Momentum Breaker on me and I wasn't able to click on a card to sacrifice.
I had 2 Ruin-Lurker Bats on the battlefield, but when the cards got blue to pick, I just couldn't pick any of the cards.
I was able to send him emotes and reactions, play with the board elements and see cards, but the creatures weren't clickables.
I just had to wait the timer to go out and then it sacrificed one at random.