Time Machine not running since El Cap install

I noticed tonight that my Time Machine hasn't run since I manually forced a backup right after I installed El Cap. I'm on a 2010 Mac Pro and my TM disk in one of the internal bays.

No errors from TM. Disk was mounted and shown. TM just said Last backup was 9/30.

However, while I could successfully do a manual backup, it would never back up it's own. If I did a manual backup at 4:30 today.....it would say next backup at 5:30. But when 5:30 came, no backup. The time would then change to 6:30.

Anyone seen anything like this? I ended up wiping the drive and starting over....will see if that solves it. Never had this behavior before.

I wiped the TM disk and started over - no help.

I wiped the TM plist file and waited - no help.

-Kevin