Description of Bug: Immortal Iron Fist’s Signature Ability Armor Breaks are not behaving as described.
Immortal Iron Fist’s Signature Ability reads as follows:
All Attacks
The Iron Fist has a 21% chance to reduce enemy Armor Rating by 446.57, but these effects are lost if concentration is broken by incoming attacks.
There is no time limit set on the armor break granted by this Signature Ability, meaning it should last indefinitely until the satisfying condition is met; in this case, that means receiving a hit would break Iron Fist’s concentration and the enemy would shrug off the debuff. This mechanic sounds similar to the passive precision buff Karnak gains in that it’s permanent, but it’s lost if you get hit.
Immortal Iron Fist has the potential to stack 2 different types of armor breaks. His other Armor Break is described as follows:
Critical Hits
The sheer force of a Critical Hit has a 55% chance to break the target’s armor and apply 428.05 armor reduction for 5 seconds.
The Critical Hit Armor Breaks seem to last for 5 seconds as described. The All Attacks Armor Breaks from the Signature Ability do not last indefinitely as the description suggests. Instead, they last for roughly 15 seconds before falling off naturally. This is not how the description states it should behave; it's a bug.
*All stats are based on a 4* Immortal Iron Fist at 4/40, level 74
The very first hit is not a critical attack, but it inflicts an armor break. This means it must be the armor break from the Signature Ability

No other armor breaks have stacked, so this is the same debuff from the first image. You can see that some time has elapsed on the debuff, despite no time being stated in the description. According to the description, the Armor Break should last until Iron Fist is hit.

Screenshot of the description:
Device and Version: iPhone SE
Device Operating System: iOS 11.4.1
Mobile Carrier: Verizon
Cellular or Wifi: Both
Game Version Installed: 20.0.1
Game Mode: Realm of Legends
Champions Affected: Immortal Iron Fist
Active Boosts: None