I'm playing with a couple of cosmetic mods though, which shouldn't affect it, but you never know, then I also play on Ironman so I can't load an older save to reproduce the bug, then the save is also in the cloud and I can't find a local copy of it anywhere on my hard drive, so I can't even provide a save of after it happened.
So maybe someone can test it on a mod free game and make a better bug report...