I always set mine after update to time.nist.gov because I don't care to use Windows as it has given me issues in the past.
A lot of us has issues a few builds back where we could not set the time server, it would error out. Some of us also could not get the sycn to work either, but that resolved it self for most of us around 14986, IIRC.
Lol - well, we are on Preview builds, so I wouldn't expect everything to work 100% corectly anyway...
Kari, I do not use Cortana at all, and am not seeing this issue. I can try to set up another VM and enable Cortana and voice and see if the issue replicates on my end, which I suspect it will...