Sometimes on the FamilySearch website, the words "Title Unavailable" appear in your Source Box instead of the title of a system source. This is a temporary system error. The part of the system that stores the source titles is currently offline.
It is a display problem only. All of the information about the source is still stored in the FamilySearch system, so you do not have to recreate or reattach any of the sources.
Check back later when the system error has been resolved.