Yeah, so, this is a bit counterintuitive, but Primo is actually particularly haematopoeitic (far more potent than testosterone).
As a general rule, androgenic potency is inversely related to hematinic potency.
So Masteron & Primo are in the same class as Anadrol, Deca, and Dianabol (a 1,4-diene, like EQ). Whereas the profoundly androgenic AAS like Halotestin & cheque drops are almost devoid of hematinic potency at doses maximally stimulatory of N retention.
Trenbolone is an interesting case. I believe that since it is used at doses far greater than that which maximally stimulates N retention as common practice nowadays (i.e., 350 mg/w is considered low dose, even though it is definitely not), its association with erythrocytosis is to be expected.