Stiff spacebar on Apple Smart Keyboard Folio

The spacebar on my Apple Smart Keyboard Folio gets stiff and freezes every few minutes. This is the keyboard without a trackpad, with a fabric-like surface, so as far as I can see there’s no keycap to pry open to check for dirt underneath. For now, I take the iPad off the folio and it just sort of starts working again. For a while. Anybody found a long-term fix?

If removing the iPad and replacing it solves the problem (albeit temporarily) it sounds like a software problem

Perhaps partly, but I think not. I can feel that the spacebar gets stiff and immobile when it stops working. Whereas when it’s working, it can be pressed.