The bug is that is has movement points.
I believe it's already fixed for the next round of data updates
WitE dev team - (aircraft data)
WitE 1.08+ dev team (data/scenario maintainer)
WitW dev team (aircraft data, partial data/scenario maintainer)
WitE2 dev team (aircraft data)
As that part of the front looks like it hasn't been activated ,where would you want to move the rail repair unit to?
Rule 11.2.5. Unlocking the Soviet Southern Front
If a Soviet national hex south or east of 187,187 (just southeast of Lvov) is Axis controlled then all of Southern Front and related airbases will be unfrozen.