Okay, I've just started playing again just to get the feel for what was happening, and the issue's not there now...
I think I know what happened:
Once the jam had finished, I opened up every browser-playable game in its own tab... Then I went to bed as I was absolutely shattered.
I then left a bit of time before starting on playing through the games, so yeah, fair to say I was playing an older build... 😅
Right, I'm going to need to update my ratings - back in a few 👍