@DumbKoala I had two or three reports like this but I'm unable to reproduce myself, regardless how hard I try. If you have a surefire way to reproduce or if you can share more info about your setup, I'd love to fix that eventually.
Errrrh ... not sure it's the same thing, but I experienced smth like that (admittedly in an older Embody version) while running the setup Wizard. I set up a dedicated scene with a default "Michael", stood in my room, ran the Wizard, spawned a mirror ... and when I possessed, Michael was trying to snap his own neck, with the hands slaved to the orientation of my Touch-controllers, while his head was trying to face 180° away from the mirror ...
I never got that fixed, no matter whether I spawned the mirror myself or let Embody do it - and after a few tries, I gave up (turns out there's few things as disorienting as having your VR avatar's head doing instant 180° turns while you're trying to remain standing on your two feet in the real world ...).
My best guess is that it may be smth to do not with Embody, but with the Occulus XR runtime - the Occulus runtime knows three settings for world coordinates: Relative, keep playspace orientation and "bedmode". If you changed your orientation after defining a playspace, but before firing up VaM, then VaM's worldspace coordinates can differ drastically depending on which setting is active in the Occulus runtime ...