IMHO, they are not releasing it because they think it might hurt them politically.
It could be true that Trump is in there, and so they are holding it back because they dont want the political fallout.....to give the Dems something to latch on to etc...I think that is the mostly likely scenario.
Another scenario could be that perhaps Trump is not in there, but important Republican allies are....and the release would tend to hurt Republicans more than Democrats......
One other possible scenario, an unlikely one, is that they are holding back to elicit a predictable response from Democrats....so when they do later release it....the Democrats lose the ability to declare it politically-driven attacks on them....since they are now demanding it....
Personally, I dont care who it hurts....release it....fock them all....