they had been unable to PM me due to me being in Eureka
This on the other hand is a technical limitation, because from what I’ve heard the instance server for dungeons/raids/eureka/diadem has no possibility for the whisper chat function. So this is not a customizable restriction option, but a physical limitation.
Eureka supports whispering to other players inside the instance, and yes, I’ve been PMed during a duty by a GM myself. It honestly sounded like the GM was just phoning it in at that point, lol.