Windows 10 PCs platform. Never been near physical xbox console but...
On upgrading to windows 10 I took the opportunity to move a child's local PC account with existing xbox games accessible to a networked account, whilst still maintaining family security control. Bad mistake. Child cannot sign on to xbox.com when starting games. Child's xbox profile does not appear under parent and attempting xbox settings access from child's account bombs out with generic run time error "server error in '/' application". Micrsoft support teams (windows, accounts and xbox) are not taking ownership of problem - 8 separate contacts and counting.
There appears to be a genuine, replicable general defect here: If you create a new account on PC and create a ****.outlook.com network account to go with it, if you trigger the local xbox app and initialise it with a child's DOB then it assigns "privacy settings: child defaults" and bombs out when signing on, presumably to xbox.com, with the wonderfully helpful generic run time error "server error in '/' application". No links to xbox.com can thereafter be re-established for the Microsoft account. Issue regardless of whether child account is or is not part of family group when accessing xbox.com to initialise. If child account is an adult - no problems in xbox.com setup.
Child has now lost achievements and purchased games access as part of "remedial" work so far. My name is mud :-(
Same diagnostics on two PCs. Anybody with any familiarity with this? Solutions welcome.