Are you guys loading it up on desktop or mobile? Google updated some procedures a couple months back so that you have to manually approve accessing data from import HTML functions On desktop, you should see a little yellow bar pop up at the top, but on mobile there's sadly nothing you can do about it. I've noticed that once you approve, it's a long time until it asks you again. More info on this
here.
If this doesn't address your issue, maybe try making a copy of the latest
sheet? I just went back into it, approved permissions, and it was operational. Lmk!