Same problem here, Big Sur 11.4, Safari 14.1.1, iPadOS 14.6 Given that this is the one thing that can only be done on a Mac, it's amazing how frequently it's either a massive nightmare to get working - or just plain doesn't work at all. In 6 years of doing this I can count on the fingers of one hand the number of times it worked smoothly. Big Sur? Bug Sur more like... eh?!