Depends how deep your data is;
For example:
Blueprint -> Properties: saves.
Blueprint -> Reference: saves.
Blueprint -> Reference Array: saves.
Blueprint -> Property Array: saves.
Blueprint -> Struct -> Properties: saves.
Blueprint -> Struct -> Reference: No.
Blueprint -> Struct -> Reference Array: No.
Blueprint -> Struct -> Property Array: saves.
Blueprint -> Struct -> Reference -> Struct…: No.
Blueprint -> Struct -> Struct -> Struct…: saves.
Also, only UProperty will be auto-saved, the plugin cannot “see” native C++ types; and everything must be marked with the “Save Game” flag.
Properties not marked SaveGame will always be ignored.