When our system is for any reason unable to validate Xbox purchases on a specific account, it will allow the player to access Save the World. This protects players who have purchased a Fortnite Founder's Pack from being locked out of the Save the World game mode.
We perform this validation check against all players, regardless of if they have purchased a Founder's Pack. As a result, when the validation check fails on Xbox One players who have never purchased a Fortnite Founder's Pack, they will temporarily gain access to the Save the World mode of Fortnite until the system catches up.
Anyone who has gained and lost access to Save the World due to the above configuration will keep all Save the World progress made during this time. Players who wish to continue playing the Save the World mode of Fortnite will need to purchase a Founder's Pack of any tier, which will allow them to pick up where they left off.
Players not wishing to purchase a Founder's Pack can still continue their Save the World progress when Fortnite becomes free-to-play in 2018 (specific date TBD).
If you have any other questions or concerns, please submit a new ticket and a member of our Player Support team will be in touch as soon as possible.