Have you tried going in to Settings, Audio and then under the Audio Output try switching and using the alternative choice to the type you've been using: If it's currently Other, try Dolby Digital, and if it's currently Dolby Digital - try other.
It's not likely to solve the problem, but you might want to try using the 1080i setting for a few minutes. (The 1080p setting was unreliable up until some months ago - so much so that it was recommended not to use it.)
And you might want to try buying a new 'High Speed' HDMI cable. This, again, is not a high probability to fix the problem, but one place to be sure you're getting the most capable HDMI cable is to go to Canada Computers and buy their version of the HDMI cables that are rated as High Speed, and specifically noted on the description as HDMI 2.0, and good for up to 4K.
And you may also try using the shortest possible HDMI cable. If you're using 6 ft long cables now - try 3 ft long. I know that about 6 years ago I was having a terrible time with my HDMI cables. I think back then I was using the SA 8300 PVR - but running my PVR through a receiver with HDMI was really flaky. I don't know if the problem was my HDMI cables were HDMI 1.3 or 1.2 cable or less.
But I would try buying a couple of HDMI cables that are as short as possible - and depending on your setup - pick up two 3 foot cables, so that you're just running 3 ft from PVR to Receiver, and 3 ft from Receiver to TV (if possible).
And you've probably already tried this - but changing the order that you turn on components may solve some problems - although it doesn't sound from your description that this is the problem in this case.
And if none of this is working, have you tried connecting the HDMI cable to a different HDMI port on your TV?
If you have more than one HDMI input on your TV - one of them will be marked as HDMI ARC - which, (and I'm not expert on this), but I believe means Audio Return Channel, and lets sound travel back from your TV to the Receiver.)
And if all that doesn't work - does your Receiver have an optical audio input? If so, you could try running an optical audio cable from your PVR to the receiver and getting sound that way.
Forgot to mention the Video output from the receiver is working fine. It is set to 1080p on the NB3.0 and the picture is as crisp as it can get.
I think I remember this from when the NB3 was introduced. Rogers broadcasts are 1080i and setting the box to 1080p causes problems.