I have experienced this a few times over the last few days. I would go into 360 setup in Composer mode and after carefully setting up the angles for the head I would preview the angles by clicking Preview button. The moment I exit the preview mode however suddenly the head drops. By drops I mean the head rotation (R) suddenly jumps from 0 to 273 for each angle that I have just configured for no obvious reason. See screen.
After that I have to go back to every angle and change the R from 273 to 0. Otherwise it stays crooked like that. I don't know if there is any magic behind the number but a couple of times it happened to me today that was the number.
I can't say it happens every time and with every character as I haven't had played with it long enough to notice any sort of pattern but I thought I'd mention it in case someone else experiences the same.
If I do discover a pattern - I'll post it.