So I tried a couple things I thought might make a difference, but no success. Still crashing on SampleTank 4.
I removed the embedded rack within the linked rack and replaced it with just the SampleTank 4 plugin. Same result.
I even tried using the VST2 version of SampleTank 4 instead of the VST3. Nope.
Hoping that IK Multimedia can identify and address the root cause quickly.