The stone is not working properly.

Good afternoon, I have a problem in the game. I have a built-in strengthening stone in the cyclone, but it does not work in the mine. Please solve this problem!

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Wiki wrote:

When you hit an enemy with a fortifying hit, you will gain a variable number of stacks, based on how much damage the hit would have dealt to the enemy...

Source: https://www.poewiki.net/wiki/Fortification


Meaning your melee dmg isnt high enough to trigger Fortify

There are always 20 fortify on the cards, but when I go to the mine there is not a single fortify.

What depth are you at in the mines? The number of fortify stacks you get per hit also depends on monster life (or, more precisely, their ailment threshold). Monster life scales with delve depth so if you are below ~500 depth, monsters will have significantly more life than monsters in maps. At some point their life will be so high that you don't get any fortification at all.

Edit:
I saw you made it to depth 572. That confirms my assumption. At that depth monsters have about 10x the life that they would normally have, so you get only a tenth of the fortify stacks. If that means you would get less than one, then you'll get none at all.