Fortify charm not working in sacred grove

Im using a charm that grants "Melee Hits have #% chance to Fortify" which i use cyclone to proc.

When im playing the map it works as intended but when i enter sacred grove in map i instantly lose all fortification and cannot gainy any until i leave sacred grove.

That same charm also grants "#% increased strenght" that i still keep when in sacred grove, So it doesnt disable whole charm, just that fortify mod.

fortify generation will vary based off how thick an enemy is, this isn't a bug(downside of playing cyclone, fortify won't be as consistent for everything)

Ok, yeah that makes sense, didnt know that.
Thanks for explenation.