they do work in Sonar 8.5.3 x64coreREverb version. Perhaps it's a setting in your Nebula3CoreII64 Reverb.xml Try increasing the rate conversion and the lookahead. <RATECONVERSION> 3559701 </RATECONVERSION> <AHEADLENGTH> 1814 </AHEADLENGTH>
Sometimes it can be worth while restricting the number of kernel processes.
Upon further investigation, I have noticed that the crash seems to be more related to how much RAM is being used, as opposed to which version of Nebula I am using (64 CoreII, Regular, etc).
It seems that when I have a low amount of RAM usage on the project (maybe 1-2GB usage), that the PRO libraries will load without much of an issue. But on larger projects (where say 3-8GB RAM usage) is where the immediate lock-up happens. My system has 12GB, so I don't get why this would happen.