The driver's side wiper arm has started to seize at the hinge point where the spring should keep it tensioned against the windscreen. The effect is that as the wiper moves up the windscreen and opens the hinge, the spring doesn't pull it back down as it lowers so the wiper is lifted off the windscreen.
Common issue? Easy fix? I tried opening and closing the hinge many times to loosen it, but could feel that the spring wasn't enough to pull it closed. Not sure if it's possible to dismantle?