Devastate Support does not work with Leap Slam + Crushing Blows

Devastate Support states that it supports any skills that hit, and when the skill inflicts a heavy stun, the enemy is immediately fully weakness broken. Leap slam says that it consumes fully broken armour to add 500% more stun buildup. I'm currently playing a Titan with the ascendancy that turns my hits into crushing blows. Crushing blows immediately Heavy stun the enemy when they reach the Primed for stun threshold.

This combination of three things make it so that when I inflict a heavy stun with a leap slam supported by devastate, the enemy is not armor broken. I would love to test out more interactions, but respecs are expensive.

I agree. I was hoping this interaction would work as well.

This has nothing to do with Crushing blows. Devastate just will straight up just not work with Leap Slam even if you don't have Crushing blows speced. It's very likely just a bugged interecation with skills that consume Armour Break, which are Leap Slam and Sunder. Neither work with Devastate whether you have Crushing Blows or not.