I'm on the fast ring, and yes, I know I'm "on insider", but I have the same problem, and I really don't know why they release builds that are more buggy than the last. From MS point of view, it probably makes sense, as they get some quality testing results, quickly and in bulk, but from a usability point of view (i.e.: mine) it's sometimes quite annoying.
Cortana and voice input has not worked for me for about 3 weeks, last two builds I think. I can live with that, but on the last build where we cannot backup/hard reset, it was annoying to lose all my outlook contacts and calendars. I had to remove my outlook account completely to get it limping again.
Should I hope the next build is better? You bet!
Will I be disappointed if it's not? You bet!
(& Yes, I'm on Insider...I signed myself up for all this pain, so I only have myself to blame.
)