Just posting to say I had the exact same issue - midi clock out enabled in Boss MS3 with midi clock receive enabled in HX Stomp. Freezing as soon as I try to make any patch changes via midi into HX Stomp. Disabling midi clock receive in HX Stomp does 'fix' the issue.
Thankfully this thread is here and I found a fix otherwise I would have no idea what was wrong.... but this should be fixed by now....