100% reproducible so far (3/3). It’s with current svn .sdd.
Transport unload must happen on an uneven piece of map, entrance to central pass on SmallDivide is just the right spot for the bug to manifest. Not all of the unloaded inf will fly, but about 1-3 of 10 do.
Edit2: looks like I just fixed it, at least I can’t reproduce it anymore. Please test.
(setting unloaded unit’s y coord correctly does the trick, our truck script was much too simplified)