In some cases a young race is placed on a world that requires no scanning whatsoever to uncover it. If this occurs it is possible to talk / trade with their race through the home planet without unlocking them as a diplomatic contact on the relations screen.
The savegame demonstrates this issue. Currently my ship is over the planet Barphikori which is the home of the Sarkab race. It's possible to talk and trade with them, but they are not present on the relations screen (With their diplomatic status being reported as "TreatyUnknown" in the planet interface).
Savegame, Character files and log
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