Actually, if you could find a clear bisection result, that would be
tremendously helpful and would probably lead to a fix.

However, with this kind of bug you need to be extremely sure about what you're
doing when bisecting. For example, if you know that the hang typically occurs
after 10 minutes, then you should play for at least one hour (perhaps even
longer) with each kernel. Otherwise, you might have just gotten lucky, and the
bisect result would be worse than useless.