This project's been driving me crazy... the code makes total sense and I couldn't find any errors with my wiring.
So I just knew it had to be a bad chip or a bad 8x8 display... because there's simply no way it could be my mistake, right?
Well, if I'd looked at the very small writing on the side of the 8x8 display I would have seen the letters TA15... on the other 8x8 are the letters TC15... I wonder what those letters mean?
This project calls for a Common Cathode... with a C. Earlier projects used a Common Anode 8x8... with an A. Hand. Hits. Head. Hard.
So, here it is... with the proper 8x8 display installed... and working fine.
I'm going to go to bed early tonight.