Mines in Fortifications against AFV

[Wiedrock]

20.4.2. Fort Level and AFV Damage
There is a small chance that attacking AFV ground elements may become damaged
during combat by mines. The probability of damage increases with the fort level,
representing the higher density of minefields.

Attacking 10times into a Fortification level 5 gives no real/serious difference to attacking into a Fortification 0 Hex. Well, I rly don't know how much of an difference it should make...thinking about Kursk.
1. MOT CUs always get some elements damaged "on their way to combat" basically
2. additionally there are some Tanks getting damaged in Combat by literally "nothing"
Not sure which one of the two is checks for "reliability", I assume one is?!
But for both I do not see a serious difference between 0 and 5 fortification levels. So I don't know where this mine damage is supposed to happen/to be observed.
Could someone clarify when/where/how/how much the mine damage is to be applied/what to be expected?

Attached is a save (modded), where you can attack with the 3 Corps in the North, the enemy's Ground element's gus have mostly been set to range/acc of 1, so shouldn't shoot.