I noticed that I was stuck on "82" cards, the number didn't go up. I refreshed the page, it stayed "82", did a card, it went up to "83", then I noticed again that it had gotten stuck on "83", so when I refreshed, it went back to "81" and got stuck there, for the third time. I stopped then.

The number is stuck both on the bar on the bottom and in the progress report.