From 3.0.1 release note:
- many NI VST plugins tend to crash on OSX when opening and closing its external editor very very quickly. This is not a Renoise bug, happens in every host, but happened quite easily in Renoise when quickly scrolling through the instrument list. Should happen less often now.
Today I’ve found that a japanese user wrote a report on the japanese anonymous forum.
Probably, it’s related to the NI VST crash issue.
When loading Sampletank 3.0.3 (AU version) with some aliases-instruments,
and the “Pin-option” for the plugin editor is ON,
then scroll through the instrument list, Renoise crashes.
This also happens when using multiple Sampletank instances too, but especially when using aliases, Renoise crash easily.
He said that the VST version works fine. It’s only the AU version problem.
I know it’s not a Renoise bug, but maybe it’s better if there is a safety timing margin to avoid such crash. 
OSX 10.9.5
Renoise 3.0.1
Sampletank 3.0.3
All 64bit
:excl: Additional info;
He said that the NI Komplete AU version also have this issue (it didn’t crash but warning message appears).