Happened to me and my dad too.
I properly changed the power system of my station to the new reactor type, worked fine. Then a while later i decided to try and put a "power (old)" to decorate something.
The instant i click : ownership of sector revoked, faction home revoked, ownership of station revoked, and the station was overheating, it disappeared at the end of the countdown.
I was able to make the overheating station part of my faction again, made it my faction home and claimed the sector on the faction bloc, but it wouldn't let me stop it from overheating.
My dad's station was also moved to the new system properly, but i don't know how it disapeared. My dad went mining and came back to nothing. Also he didn't save any blueprint of his station and lost everything he worked on this whole week ...