Don’t try to look too close at the immediate fault cause. In an RTOS, typically the code that caused that problem took place long before something else crashes.
I’m not familiar with the 68k port (though I coded for the 68332 and a ColdFire POD many many years).
What I’m interested in is the context switching mechanism. Normally this goes through a software interrupt. Which one is that and what priority is that one assigned to?
Coincidentally, the only issue I ever created in this forum actually dealt with an 68k derivate (ColdFire). Maybe some of the info in there is useful to you (the fault cause actually was exactly that - a problem in the context switch interrupt priority):