Mainstage tuck on Scanning Audio Units (finalized 0 of 10)

I recently reinstalled Native Instruments Komplete 8, as it seemed some of the browser UI had broken since I updated my MacBookPro to Yosemite a few months ago. After the arduous uninstall and reinstall process, I updated all my NI plugs to the latest version.
Bad idea. Now when I boot up Mainstage 3, it gets stuck scanning Audio Units. And the ten it is stuck on are the Native instruments---Absynth, Battery, FM8, Massive, etc. So I tell it to abort, so I can at least get to work on MainStage without my Native Instruments.
What's strange is that all these NI instruments operate fully as standalones. Stranger still, when I boot up Reaper, my DAW, it can load all these instruments not just as VSTs but as AUs. Which suggests there isn't anything wrong with the Komplete AU .components themselves, but rather how Mainstage handles them.

I tried:

repairing disk permissions

deleting Macintosh HD > Users > your_name_here > Library > Caches > AudioUnitCache as well as com.apple.audiounits.cache. Tthis forced a rebuild of the file, and it had no problem scanning the other 30+ non-NI AUs I have---but it actually made it so I couldn't see Kontakt as well. To get kontakt seen again, I rescued both of those cache files from the Trash. Still, though, not sure why Kontakt works but none of the other Komplete AUs work.

Any suggestions would be appreciated, I rely on Mainstage 3 now as my main gigging setup, and many of my sounds are made with NI instruments, so I'm kinda screwed until I fix this!

Thank you