as stated in this Steam forum post, I witnessed some trucks traveling through a star gate ... with no return >.<
https://steamcommunity.com/app/1594320/discussions/0/806848929007309737/
original text:

"I just witnessed 6 trucks disappearing into oblivion. They happened to path over a railway crossing, that I started to deconstruct a few seconds ago. I used some of my little unity to remove it, but I only had enough for one half of it (the half on the other sinde of the crossing). The one part got deconstructed, but the rest was in regular “will be deconstructed soon” colored red.
Then the first truck arrived, drove right over the first part of the close to be removed crossing, and then he disappeared. I could not believe what I was witnessing in that very moment, but soon some more followed. I watched my truck count closely, and with every truck vanishing, the truck count lowered. From 100 .. to 99 .. to 98 down to 94! Finally I had enough unity again to remove the full thing and the vanishing stopped. Luckily.
Rest in pieces …

As soon as I get some more time, I will try to reproduce that to verify the situation and report. Did anyone else ever had a similar case?"

Encountered this myself. It's got some pretty clear steps.

1. Have a railroad crossing.
2. Have truck traffic on that crossing. It's easier with heavy traffic.
3. While the trucks are approaching the crossing and close enough they won't refresh their path before they get there, deconstruct the far side of the crossing, but leave the near side valid- so they can still enter the crossing, but can't exit.
4. Unity deconstruct is not necessary. Simply marking for destruction is enough.
5. Watch the trucks enter the crossing, encounter the deconstructing exit... and vanish. I only had two disappear, and total truck count did not go down, are they teleporting to vehicle depots? I have two of those too.

Workaround/prevention:

1. Deconstruct the near side first.
2. Unity-deconstruct not necessary, just marking it for deconstruction is enough to force approaching trucks to reroute.

Version 4.1 | v0.8.4b (b593)