Yes, in the end I had to return it.This is from their site.
UPDATE NOV 2017: We have made a tweak to the latest batch to improve compatibility with Android for this Type-C DAC. This removes the "skipping" issues previously reported with some phones.
UPDATE NOV 2016: Android 6.X and 7X introduced a bug when this DAC is used with some phones (Nexus, Samsung). It works if you put it in Airplane mode. The problem doesn't occur on computers (Macbooks etc).
If the included adaptor with the phone works without issue I'd get ahold of HiFime and see if they'd replace it.
Shame, sound was good (when it worked) and size was perfect. Now I'm on the hunt for another DAC which is small and has decent sound, and an usb-c connection (other than Google's, whose sound quality I don't like).