Thanks for this, I had the issue with a much earlier build (been running it for a couple months now), I guess they never fixed that.
There is also a known issue where if you have not installed the latest firmware update (June 11th? I think) and you install 8.1 preview, the firmware update won't install (this is my biggest issue at this time). I have a bug submitted for this one.
I've still been digging in and posting other bugs as I see them, but feel free to provide feedback though the normal channels. I will keep an eye here to see if I can help.
(I am a Microsoft Employee).
Thanks!