I just did some quick research on this. And there seem to be a couple of "problems".
First, might be similar to Ostarines gyno problems. Whereas the anabolic compound acts strongly on shbg (thus freeing up a lot of test that later on converts to e2) but fails to act as an androgen (dht) that would counteract e2 at the breast tissue. This would be specifically pronunced at people who have high shbg to begin with at the start of the cycle.
The second problem is that epistane, under heat, apparently converts to DMT (pheraplex, not the psychoactive drug). Pheraplex can cause gyno by prolactin. How readily this conversion happens I don't know. I would asume that the older the bottle and the more the product wasnt produced with high production standards, the more chances are of this.
Thirdly, one epistane product was once found to be just straight up mixed with pheraplex. And judging from this, and knowing these supp companies can basically be "labs" in the owners garage, you can't trust what's in them at all.
And for the last point, this is what evolutionary (i know, i know ...) cites: "It is true that Epistane should never convert to the illegal Pheraplex. The only reason this ProHormone got a bad reputation for converting to a banned substance while sitting in storage for too long, is because some of the “cloned” Epistane products were using 17alpha-methyl 2beta,3beta-epithio 5alpha-androstane, instead of the real true compound: 2a,3a-epithio-17a-methyl-5a-androstan-17b-ol., which should never convert to Pheraplex ."
So, there are a lot of reasons why people seem to be getting gyno problems from epi products. If it is the first point, assuming that it's reall epi and nothing more, then the low shbg - high e2 problem should go away on it's own while the user's testosterone production gets suppressed. And the gyno problem should only show as itchy nipps and not proceed to lumps. This is however hard to predict, as some might get shutdown sooner then later. Also some people might be more probe to gyno then others. If you are getting itchy nipps from temporarily high e2, then you had some underlying gyno problems to begin with, probably. This is not uncommon at all.
If epistane is cycled with other compounds, then the first option should not happen at all. Either way, I wouldn't cycle epi due to all of this. Just buy some var or tbol or even sd, from a reputable ugl. Or do take epi but use it with a dht. But have some caber at hand if it does end up converting to pheraplex? Nah, to many variables ... just don't use epi at all : )