After the lastest update to nerf vampire coast rampant expansion, it seems that the Vampire Counts have suffered the same fate. Vampire Counts seem to refuse to fight and are stuck at their starting position while The Empire are rampantly attacking them and fending them off.
Something I did noticed, since I am a modder, is that CA changed the Vampire playstyle all together. Here's a comparission picture from the old Norsca patch and current version:
"Old" is the old Norsca Patch, while "Current" is the current patch of Warhammer 2. I speculate that all Vampire factions that share these formulas are now very defensive in their attitude, which will halt their aggressive behaviour. Making them look like frightened cowards.
I believe this is because CA rushed this decision and this edited ALL Vampire AI details, which undesirably affected Vampire Counts as well.