Well, I decided to return my U12 to Amazon and buy another. I can only assume the unit is faulty at this point. @conquerator2 had a faulty U12 for his first unit, but his replacement one works fine with his Theta (which is the exact same model as mine). Given that, and everything else about the situation, I think it's worth trying another unit to see.
I'll know on Tuesday if it works or not. If not, I'll have to look into an alternative to the U12. :-/
I'll know on Tuesday if it works or not. If not, I'll have to look into an alternative to the U12. :-/