Thank you so much for the replies! I called Wacom today and they told me to use the older version 6.3.15 driver and that worked perfectly.
Wacom Software Free
He said what the issue was is that with the latest driver for MacOS Sierra retired the support for the 21ux. He said I should have any issues at all cause there wasn't a huge change between El Captian and Sierra.
Wacom For Mac
So that's the good news. The bad news however, is that this year I'll have to be upgrading to a newer Cintiq which is $2,500+ since Mac will most likely debut a new OS this year per their style. Which is a 'Yay new toy!' Moment but 'Boo I hope I can pay rent' kind of thing too hahahaha.