Bug roaming defense troops

Ok this has been a thorn in my side for a while now. I like the roamers but what i don’t like is when regular troops bug out and become immortal and untargetable. They seem to turn into those roaming troops, gaining no xp moving extremely slow but you can still select them and send them around and attack. I just fought and impossible battle against lorien brutal ai with isengard wotr where cairn amroth sentinels bugged out and became immortal killing machines wiping out slowly but surely my entire besieging army. That’s another issue actually. Does the ai have an insane damage and health boost in wotr from the get go? I don’t think they get stronger with territory bonuses or something, they just pwn in the beginning and suck at the end. If this doesn’t work to balance maybe get rid of all the territory bonuses for attack and defense, and balance the ai boni accordingly. I get a feeling the bonus can’t be scaled the further you go into a game, so i suggest to remove it all together

This happened to my troops on another map when playing gondor, so the bug is universal i think. This happens when a troop is close to their base where the roamers spawn from barracks etc. and the battalion looses a lot of troops, eventually they turn into roamers, i never encountered them this immortal and potent though...

This is a vanilla bug and has not been fixed yet in the vanilla game.