Geo soldier Tenacity down in Geo TB-why it's sometimes not applied?

It is my understanding, that tenacity down is a status that can not be resisted.

Geosoldier has tenacity down on his basic, so he should apply it always when he assists to geos.

I've seen it multiple times, when it's not applied on toons in GeoTB. I have to attack sometimes two times before it's applied. Don't have a movie yet, but I'll provide one in later phase. Is it something I'm missing here?