In an effort to share more information with the ALiVE team, I'm going to post some more of my findings here. First off, here's a link to the feedback article submitted to BI. I apologize for the laziness, but I'm at work right now. There are a couple RPTs there from crashes with all of our mods so not sure how helpful that will be.
We started having crashes as well shortly after 1.54 hit, as a matter of fact, I don't recall having any crashes until after we updated ACE3 to 3.4.0 (their first update following 1.54). When the "crash" happens, everyone online appears to be running in place as if there were some kind of network problem, but we don't receive any "no message received" messages. The RPT logs will be filled will cannot send message to player X (you'll see an example in the RPTs I linked).
During testing, we tried a "low mods" configuration and only ran CBA, ACE3, RHS (US & RU), and ALiVE. With a new mission created with just those mods, we still experienced a crash. Sadly, I don't have the RPT for that.
The above mentioned crash along with the fact that we are now stable that we have removed ALiVE from our missions, leads me to believe that the crashes are caused by some kind of conflict with ALiVE and ACE3 or RHS. If I can convince a few people in our unit to volunteer, I'll try just ALiVE and RHS and see what happens.