It isn't a bug at all. The trailers are made to spawn only if the game detects country signatures such as: "DK, NOR, SWE". There is no physical way of them spawning anywhere else, you can edit a save and change the destination, but good luck with that.
Now there is a part to it that admins play, since the trailer normally spawns to Denmark, but according to some of the admins Denmark isn't in Scandinavia and you can't deliver anything there xD
Run TruckersMP and click on download wait for it to sort it's self out and run ETS2 or ATS.