Why am I sometimes not getting 3-4 Abyss cracks?

I am using: Sextant, Map Device, Gilded Scarab, Wandering Path with all +Abyss nodes (64% inc chance)

I am very careful to make sure I am not accidentally triggering them.

In the last 4 maps, I had: 3, 1, 2, 4.

This is still a regular thing. Doing the T7 Cemetery strat. Just had a map with 1 abyss. The drop down menu for map said it contained 3 additional.

I was getting 1 all the time, had to stop doing any other mechanics whatsoever and it still doesn't help. Strongboxes, Legions, Blight, Harbi even tormented folks seem to impact it.

but I'm not sure i am buying into this as a reason - I had a map with 4 abysses, legion, harbi, Deli, tormented spirits and a breach.

and I also had a map with zero mechanics and just one abyss (drop down claiming 3 extra abysses).

This is a bug.