Have the same problem on my 12.9 2nd gen iPad Pro. Was hoping for a fix but looks like that won't happen, 12.2 has made no change. I have noticed it happens if I put the iPad at certain angles, and more often if I'm on a surface that would generate more static electricity (like laying in bed) than if I was say sitting at a desk. I assume this is some type of electrical interference issue between magnets orientation and static electricity, only guess I've come up with. Super frustrating no matter what it is, for something I spent $1300 on it is inexcusable. And of course it starts happening after 1 year warranty runs out.