Maybe it’s unintentional, but still, according to gamepdia, and it contains also new purge types so I believe is updated, the only types of purge that could have place in B7 and I7 at level 6 of difficulties do not contains any human at all.
A friend of mine playing the game in Solo changed purge settigs (to difficulty level 6), because he supposed to obtain with more chance t4 thralls and he never had an human purge at all like @Jim1.
Restoring default setting it worked all just fine.
That’s why I supposed to be the same problem.
EDIT: personally I always played on online server I never owned, so I never changed/see settings and I don’t know how they work.
So I don’t know if the problem is a miserunderstaning of how they work by players changing them or a bug in how they was supposed to be working.
I’m limiting myself reporting a fact: You always obtain difficulty 6 purges if you change to 6 the default value in purge settings, and there are very few purge types having humans at level 6 (and they can’t spawn in all areas of the map).
EDIT2: maybe you noticed I’m not native english speaker, so if I miserunderstood what are you trying to state or I was unable to explain in details what I’m trying to say, my apologies