Account attached to Xbox Live Gold works fine, others do not.
Other family member without Live but using same Xbox set to Home does not have access to Realms or Worlds. Power cycled Xbox, removed affected player and added player back, and called Microsoft to refresh the account. Problem still exists: players without Live using a Xbox One set to Home with an active Live account ID cannot connect to realms or worlds. Not an issue on Minecraft Xbox One Edition. Issue on new Together/Bedrock version of Minecraft