Derelict Mansion Map only contained 2 Ritual alters

I ran a T15 derelict mansion 6 mod map today that seemed to have a generation bug. The map itself was "Overrun by the abyss", and I used a ritual, irradiated, and empowering tablet. The first floor only contained the 2 bosses in the center and no other mobs. The upstairs contained:
- 2 spirits
- 1 Essence mob
- 1 abyss
- 2 Ritual alters

I've been spec'd into "Spreading Darkness" (always have 4 ritual alters) for a while now. I've also ran an abyssal overrun derelict mansion before, and it contained 4 alters with mobs spread out on both levels, and the correct number of "Additional Abysses". Overall the map had 3 total rares including the essence and barely 50 mobs!

The mods for the map: