Interaction between heavy stun, armor break and freeze prevents heavy stun

When 1 player freezes a unique boss and another player heavy stuns+armor breaks them, in some combinations of interactions of these effects the heavy stun can no longer be applied, regardless of if the stun meter is brown or orange. The freeze can be reapplied.

When it occurs, we can wait after a freeze, until the stun bar turns brown again, we can stop applying cold/freeze, I can fully fill up the brown stun bar with stuns but when it fills up it never ticks over/never turns orange, does not apply armor break on heavy stun.

It is possible that it is a visual bug, but I doubt it.