This happens all the time, and it has made Memrise unusable for me at the moment.
If it helps shed some light on the matter: my iPad broke a few months ago, and I stopped using Memrise until I bought a new iPad Air last week. This means that I had not used the app for a few months, and that it’s an iPad where everything has just been restored from an iCloud backup.
Using a 5th generation iPad Air, with iOS15.6.1 and v2023.2.6.57544 of the Memrise app.
It should be completely fixed already, yes.
I had a try on the website and it worked well for me - so maybe it’s just a sync issue with your device. Does it work if you close the app and reopen it? Maybe you can also try to log out and back in?