Same test as Bioshift, ambient enemies of first area on each map, 30 restarts each.
Festering Ground:
Beastmen 10%
Chaos: 33.3%
Skaven: 56.7%
Fort Brachsenbrucke:
Beastmen:10%
Chaos:20%
Skaven:70%
Halescourge:
Beastmen: 40%
Chaos: 36.66%
Skaven: 23.33%
Screaming Bell:
Beastmen: 13.3%
Chaos: 40%
Skaven: 46.6%
I haven’t seen a map with as much of a beastmen presence post-patch as Halescourge, does seem like an exception compared to the other 3.