Not sure if helpful, but I'll add to this:
Wife and I play together. I'm host.
So far, every time I pull out the mk1/2 lift, my wife will crash. Upgrading to the mk2 belt has the same effect. Wife also crashes if she attempts to build the lift.
If my wife immediately tries to reconnect after the crash, she will crash again, then I crash. Reloading as host before she attempts to reconnect seems to prevent further crashing until I whip out another lift. Havent tested with mk3/4 yet.