I've been trying every which way to get this to work. Office 365 Admin, Azure Directory, Sharepoint Site, everything.
I have a few team members that will not come up in the Add People to Schedule box. Despite being in no other Team or on any other Schedule, I cannot get them added to the Schedule that they're a Team member of.
Even making them Team Owners has no effect. It appears random and only affects a few members in differing Teams.