It happens anytime I try saving pass a certain amount of exploration, I have auto save off, and it doesn't block any other tab, only the menu and save buttons
It seems almost random when it happens but might have something to do with all 3 save files, yesterday I reset a world and saved at the start without progressing and today when I went back to that jungle world I was able to uncover the bottom left portion and a bit of the top left of the map before being blocked from saving but when I went over to that new world I encountered the save prevention way sooner, this is as far as I got in the new world before the bug triggers on the next step