Dexterity Pop-Up but not evading

mum_m2

Excuse me if this is a repeat but couldn't find anything on this.

When I attempt to perform a deep evade from block stance, dexterity will trigger, but it will not evade the incoming attack. This is causing unintended block damage.

(So I totally get it if i'm evading too late in my deep evade, but if that's the case why does dexterity pop up WITH the buff)