You have a source on that? All I've read so far as that there remains a NYS investigation which may result in charges if Trump decides to pardon Manafort. I haven't seen anything about Mueller holding back charges.
It’s speculation but to me it sure sounds pretty plausible to me as Mueller isn’t charging things he clearly could.
http://www.slate.com/articles/news_...trategy_for_outmaneuvering_trump_pardons.html