SOLVED!
Well I've never seen that before.
The overview article I mentioned, which also wasn't updating, I had said to a sticky post (so it was always in position 1).
I've just "unstickied" the post (the event is over anyway) and the front page and the article page have both updated (checked in incognito).
Now I don't know if this is a known WordPress issue or some very weird combination. I rarely use sticky posts.
Apologies as it most likely isn't an Ezoic issue directly! Perhaps at some point I'll check on one of my other WP blogs (non-Ezoic) with a sticky post and see if I can replicate it.