Unfortunately, the error bug occurs when Reverse Engineering Dread Guard Relics, period. My question above is regarding instances you get the error but also get the message that you've successfully learned a Schematic. We want to be sure that when you're told you learn a new Schematic, that you actually do! I've edited my message above to better relay that. Sorry for being unclear!
Understood, thanks for clarifying!
Maybe I should make another thread for this, but is it intended that schems cannot be learned (No Research Available) from Arkanian relics sold by the vendor? (Not sure if it's true for Underworld as well.) DG/Campaign relics could always be learnt from the vendor versions.