yup, i realized this too, when making several of my mods.
no idea why. but its annoying as hell. However, you can use engageplayerpos to fix it.
I found that on MP, anything in the first 3 variables are wiped to 0. last 3 are intact. so if you wanted you're engageplayerpos to be -1, 10, 0, 1, -10, 0 -- you can just shift all the env_obj and change the engageplayerpos to 0,0,0,2,20,0.
Aside from that, no fix that i know of. Still, post it in support, i've told hampa about several mod bugs, he says he'll try to fix them before the next release, but he has to know about them. Post in support so that he can have a "record" of them.