Update: Fallout 4 is listed as unavailable on the Xbox Store now, so it appears they are in the process of fixing it. Original Story is below.
Something strange has happened today as the Xbox One version of Fallout 4 is currently free via the Xbox Live Marketplace. There have been times that this has happened in the past, sometimes all of the free versions of the games are redacted and there have been other cases where the free versions of digital titles have remained free.
Bethesda has yet to make a comment on this change in the pricing on the Xbox Marketplace but it is expected to be fixed shortly. It is possible that all copies of Fallout 4 bought through this will be removed from users library's. We will continue to update this story as the situation changes.