i had been able to reproduce the event it took me few weeks but...
ok i had been playing around with mekhq versions from late .0.45.XX and i had no issues of MM freezing up or just hanging.
the issue started to appear in 0.46.XX versions and on all the way to the current one i am using 0.47.6 i at first did not pay attention since i play MHQ on and off so never really caught it but over several weeks i was able to repeat the issue.
from options inititiave rules in MM any thing with simultenious in it in but deployment