Devastate Support (Armour Break) not working on Sunder

I´m playing Warrior/Titan with Culling Strike on Hit, with Sunder as main skill.

I skilled into Stun Buildup, so that - together with Culling Strike - the majority of enemies get "Heavy Stun" with one-hit of Sunder.
I socketed "Devastate" (Fully Breaks Armour on Heavy Stun) together with "Armor Explosion" (Explosion on Fully Break Armour), but I do not get "Fully Armour Break" and therefore also no explosion, despite "heavy stun" the enemy.

The very same support skill gem combination is working with different skill gems (Rolling Slam, Mace Strike, ...) but not with Sunder. Both support skill gems are compatible with Sunder, as of the tool tips.

Any ideas what is wrong with this setup?

Thank you very much!

Seconding this issue.

It also does not function on "Leap Slam" either despite saying it is supported, the only skill I could get it to work on was the basic "Mace Strike."

This also affects the "Splinter" support gem as "Leap Slam" and "Sunder" do not break any armor from their damage using it but "Mace Strike" does.

Yep same for me doesnt work at all on Sunder…

I thought this might have been a bug at first as well but I think the Payoff text on Sunder prevents it from applying armour break:

Sunder fully consumes armour break on enemies for a guaranteed crit

But I think then it would definitely tell in the description. And as this bug also occurs with Leap Slam, where no Armour Break interaction is mentioned at all, so I still assume its just not correctly functioning at the moment, unfortunately.

Same issue. Sunder together with Devastate or Splinter don't break armour, even though they are both compatible with Sunder based on tooltip (checkmark). These two supports worked with default attack.

it is also not working on Leap slam...

Sunder *literally* says it CANNOT BREAK ARMOUR

So I don't know why you guys expected.

Definitely a bug with Leap Slam though.

Could you define how *literally* it says that?

The text says that sunder *Consumes Fully broken armor*, thus the sequence with slotted gem should be:
First hit: fully broken armor applied (given heavy stun)
Second hit: fully broken armor consumed.

Can confirm that no full broken armor is applied given heavy stun happened.

Second this.

Is this to prevent the skill from being broken or a bug?