Encountered the same problem today (30/12/2020)
Got my truck towed away (via service menu) to the next service (in Sofia) and got over the border this way
Hi I discovered a problem at the border crossing to Sofia see screenshot.
If you want to cross the border it won't work. the screen of control does not open and you cannot cross the border
The bug is still there.
A recommended way to avoid this bug is either to drive on the grass or you can call the service (but it will cost you some euros)
ETS2:Promods+RusMap+The Great Steppe+Middle East+Red Sea+Road to Asia+SibirMap+Paris Rebuild+Finnmark(+Maghreb in the future)
ATS:Promods+Reforma Map
Came here to report this one, both checkpoints are broken. The border patrol starts but then nothing else happens.
You can drive around it on the grass though.