Okay, I had a weird bug last night. I had stepped out of my power armor at The Slog to repair the defenses after a particularly nasty raider attack (a crazy legendary raider had got really deep inside the compound) when I heard some shooting to the north. I didn't go for the power armor, but ran straight for the fighting. It seemed an assaultron and a mr gutsy were attacking a trader and his brahmin so I intervened with my plasma rifle (though I made a quicksave before attacking just to be safe; assaultrons are insane with their sun-in-the-head laser thing). After looting the robots I headed back to the power armor and fast traveled to another settlement which was under attack. When I arrived, there were two yua guai wreaking havoc in the camp but I dispatched them too. I stepped out of the power armor to fix the defenses and assign some slackers. When done, I went for the power armor to find it gone and this settler in its place:
So I tried to talk to her, but she was locked into thanking me for saving them; no matter how many times I talked to her, I got the same dialogue options.
Okay so 'bugged'. I reloaded my quicksave, killed the assaultron and mr gutsy and ran to the power armor at The Slog. Now the power armor can't be interacted with. Well, well, well. I saved a proper save and quit the game. Maybe it will be fixed when I play tonight? Maybe the game was in a weird state and somehow this bug is transient and not inside the save file.
If not, I have lost my only power armor chassis and all my upgraded parts (it was a model t45e, but model d should be in the workbench inventory).