Just so everyone knows...
The previous version of After Effects (CC 12.0) will not work with OS X 10.9.4. So if you want to go back to a version of AE that works with R3D files, don't update your OS.
Really frustrating, and I hope they get this fixed soon.
Edit: My laptop is running OS X 10.9.4 and AE CC works with it. I checked and it's running AE CC 12.2.1.5
So how do I get that version on my Mac Pro? When I use the Creative Cloud App and choose previous versions It allows me to download CC 12.0. I've checked for system updates and nothing comes up. In the CC app I don't have a choice to update applications - only to upgrade to CC14.
Any thoughts on how to get the previous version working so I can get back to my R3D files without spending twice as much time forcing a program to work than I spend actually working in it?