Error [104]

I also have the same problem; Can play Apex Legends just fine on my own account (Adult, has the XBL subscription) but by teenage son can not play using his own account / gamertag (member of the family, has XBL subscription shared with me), presumably because it is still a child account and I can't 'promote' to an adult account until he is 18. It really bugs me that we have such inadequate controls as parents (that's on the MS side) but also that publishers do such a half-assed job of deferring to the parental controls implemented by MS. For Apex Legends the fact that he has a child account seems to override his age or any of the content ratings I specify for his account.. and I am in a position where the controls that are put in place to safeguard must be entirely circumvented with a new adult account for him (so I can lie about his DoB etc) instead of EA (and MS) sorting their s**t out.