In the last couple of days I’ve constantly hitting this message while reviewing:
Nothing really changed on my end, so I figured it was something temporary and I should try another time. But it keep happening no matter what time of the day. I can’t figure out a pattern either. It is always during review, but sometimes it is almost immediately and sometimes it is later when I should be finishing for the session.
PS: refreshing the page does “fix” the issue, in the sense it goes back to the reviews. But it completely reset the session, forgetting the pending mistakes. Not terribly sure how much of the ones I did get right it saves but it is at least some of them.