Really all of it is in my original post. My son's game save re-appeared which was interesting, my daughter quit playing on her save, she got tired of restarting. Now she just joins my world when I play (I'll load the game streaming from cloud or last resort use my older Xbox 1S.) So it's sort of gone away for us sort of.
1. Xbox Series X (most current version of the game since it auto-updates.)
2. Both
3. my kids play grounded they have lost their game saves/progress every time they play.
4. Played the game with auto save turned on, saved game on exit, the next day they'd start the game up and no saves would be present. Meanwhile I myself have never experienced this problem, my game always saves my progress.
Can't say I really want to generate a support ticket at this point because it doesn't seem to be happening....I guess I could sign in as my daughter and see if her game saves show up. Not sure how to reproduce it when she's not playin in her own world anymore.