PT12HD AAE -6101 Error

This is the first project with VIs I have tried using PT12HD.
Cannot work in PT12HD with Omnisphere 2 without show stopping CPU AAE -6101 Errors. 4 midi tracks only. nothing else in session. 48k 24bit. (Have not tried other VIs yet, but somehow expecting the worst). Buffer at 1024. Dynamic Plugin Processing enabled. System Usage Meter shows only Core #4 being accessed. Core 4 goes up to 50%, but Total CPU meter at top goes all the way up to high 90s then - AAE -6101 Error.

Very disappointing......

Saved standard midifile.
Tried same exact session with Omni 2 in Logic Pro X.
Not a hiccup!

Any help or thoughts would be appreciated.
Thanks!

PT12HD 12.0.0
UA Apollo 8 Thunderbolt
iMac Retina 5k
4GHz Intel Core i7
24GB RAM
1TB fusion drive (I thought these were okay now)
Plenty of Disk Space
Omnisphere 2 Library on Sample Drive (not system drive)