I think we have a couple winners in the contest!!

Marked the cup, lock ring and shell per Andrew's suggestion and rode the cranks off of the bike. All the marks are still aligned, so dsbrandtjr's theory must be correct as the BB is too loose to continue riding. Must be the threads on the cup. I'm hoping the UN-55 with both ends thread supported will solve the issue. Banging my head against a wall instead of spending $25, duh!

Thanks everyone!