The chipsets were outsourced to Taiwan-based ASMedia Technology for R&D, are rumoured to be seeing design issues, which will increase motherboard players' costs by US$2-5.

According to Digitimes the Zen processors themselves seeing a stable development and have a satisfactory yield rate, and entering the engineering sample stage. Both motherboard players are seeing the chipsets designed by ASMedia having some issues over USB 3.1.

The Zen chipsets' have design limitations so that USB 3.1 transmission speeds drop dramatically as circuit distance increases. This means that PC and motherboard players to add additional retimer and redriver chips or even an independent USB 3.1 IC to get it all to go.
This has increased the makers' costs, not by a huge amount but just enough to be really annoying.

AMD is considering acquiring retimer and redriver chips via third-party suppliers to sell along with the Zen chipsets, but so far the sources have not yet heard any firm details on costs or development.

AMD is not saying anything other and ASMedia insists that this is all a market rumour and everything is fine, nothing to see here move on please.