A little update: I'm still poking at it, because I can't finish the design without it (and if I don't finish it, I don't get paid).
It worked for an hour or so, then stopped working again. It worked long enough for me to spot some oddities, the biggest being that if you turn off the reset input it still creates one and forces you to export the conduit.
While I was trying to figure that one out it stopped working - now it's back to the hang situation.
When it hangs it takes one CPU core up to 100% and keeps it there - the longest I've waited is 15 minutes - and you have to kill it to get back to Qsys.
For "fun" I installed 14.1 on a different machine. It behaves the same way, and (oddly) when one works the other will work, and when one hangs the other will hang. This is on two different machines, two different versions of Linux, and two different versions of Quartus. The only thing that's consistent with the crash/hang is the time of day.