Fortify Mastery - Recover 100 Life for each Fortification lost

Recover 100 Life for each Fortification lost.
Does "lost" mean refreshed? In intense fights I always have max Fortification stacks. Does "Recover 100 Life for each Fortification lost" work when a new Fortification replaces an old one.

Thank you.

I too would like to know .

https://www.poewiki.net/wiki/Fortification#Mechanics

"The fortification mastery that grants Recover 100 Life for each Fortification Lost does not recover life when you lose instances of fortify while you are still at maximum fortification; you only gain life when your displayed amount of fortification decreases."

Edit: The mastery basically exists for some niche interactions that temporarily increase your maximum Fortification stacks, such as the +max fortification while focused unveil/craft.