Phone does a half ring or maybe a full ring and then gone...nothing in the log showing who called and then up pops a voicemail...i have to get this corrected for my business and lost calls!
I had the exact same issue on my non rooted note 3. It happened right after the hd calling update. The sprint store tried for over an hour to solve with no luck. They recommended that i do a factory reset. The reset worked. I have not had the issue since.
I have experienced this exact same issue. It only happens when I try to set the lock screen to "none" as long as I have the lock screen enabled, the phone receives calls correctly. I first noticed this issue when I tried to use a 3rd party lock screen and disabled the factory one. I hope this helps you.