Break 100% armour does not fully break Unique monster armour

I cannot find any information about Unique monsters resisting armour break, so unclear if this is intentional or a bug:

-With Shattering Blow (break 50% armour on heavy stunning an enemy) and 100% increased armour break on tree, heavy stuns will apply fully broken armour to rares, but not uniques. (no armour break on support gems/jewels/gear)

-With Shattering Blow and 105% increased armour break on tree, heavy stuns will apply fully broken armour to all monsters, including uniques.

This seems odd, but its clear that you need to break MORE than 100% of armour to apply fully broken armour to unique monsters.

This is a known issue with both games. Sometimes the game randomly decides to round down, so you need sligthly over 100% to actually get the full effect.