Pack Size might not work with Undead mod on Maps

I've ran a lot of maps and a lot of crematoriums with this character and a lot of maps in general and and this map seemed to have abysmal mob density compared to most maps:

Area has patches of burning ground
Area is inhabited by undead
+40% monster pack size
-19% maximum player resistance
monsters deal 88% extra damage as cold
Monsters' skills chain 2 additional times

I think on some of the floors I found less than 40 monsters... I ran into super small pack sizes and the biggest pack size was probably 12 monsters. I just feel like there was something wrong with the map mods regarding pack size and undead on the crematorium map. Overall I could find at least 2x more monsters on an average white unmodded map.