Potential Bishop bug?

Fluxxy

Hey folks so I just wanted to get clarification about the way bishops specials interact with unblockable nodes. In a dungeon run just past we both had unblockable specials and it appears as if both of his specials cannot be blocked after the initial hit. Which when it comes to his s2 is brutal af, luckily I had ultron lol.

Is this by design or a bug? Cheers!