Well, yes there is an obvious explanation for this.
Much as most people have already guessed Wikileaks has a clear pro-Russian bias and they have been proven to "leak" altered material that was specifically doctored to make USA or certain political candidates look bad.
Which really is a shame because there was a time when it did some good. Unfortunately by being clearly biased Wikileaks has become untrustworthy and even if they find and reveal some important leaks now, no one can take their word for it without doing a rigorous check on the data. ...Which is practically impossible due to the nature of the leaks.
TL;DR Wikileaks can no longer do what it was supposed to do. It is not a neutral and trustworthy source of information.