Slate is kind of buggy in general, even in Pro Tools which is one of the main DAWs of course. I used to beta test for Slate and stopped because I can’t stand Steven Slate
I’ll give him credit that his drum trigger was and maybe still is the best there ever was, but in general, he has a quality vs. quantity problem with his products. I would write to Slate support and ask if they actually test their plugins in WaveLab anymore, or if they just test Cubase/Nuendo. My guess is they don’t really test WaveLab specifically, but maybe the crash reports will help them locate the problem and update their plugins.
I do still use Eiosis AirEQ which is built on the Slate framework (same developer) but I haven’t tried to use anything Slate in WaveLab (or elsewhere) in a few years.
I would look elsewhere IMO