As confirmed multiple times in this thread, we are looking into that. And, BTW, the save is working just fine, what is not working is the Load.
There's a (obviously TEMPORARY) workaround, if you open the aircraft editor in 2D and change anything, like a door name, it will work for that session, until the next restart. This because your saved file is fine.
However, if you enter directly in the 3D editor without doing first, you'll have to fix your doors again, that is the real problem.
