Wanderlust "Your speed is unaffected by slows" still got slowed by Act 2/5 boss Slowing Shock

I suppose this might be intended given GGG propensity to create many different slowing and movement impairing effects, but given the changed wording of Action Speed and Slows in P2, I think this may be a bug.

I got hit by the Act 2/5 boss's shock thing, I guess from the stationary objects, the resulting effect is the same as getting hit by the Minotaur shocking beams in P1. Same icon in the top left also.

Despite wearing Wanderlust "Your speed is unaffected by Slows", my movement speed was in fact reduced.