Hello.
After months of on and off research into why the rewards app did not work for me, I finally have the answer.
I put six (6) Android devices to work, each with monitoring software of various types.
The bottom line is, latency.
At least for me.
If ones connection rate is below a certain threshold, the latency too high, then the SSL certificate handshake will be denied by the ad server. Sometimes this results in no connection, other times in no ads.
I have found that a data rate of 48Kbs is the minimal requirement.
So, if one is as I, on a phone, in an area with poor coverage (or a signal below 35ASU), and bouncing connections through a proxy, over a VPN, and with multiple connected devices, the result can be extremely frustrating.
Note that this is not a requirement of the app itself, rather, of the ad server.
As the app doesn't report connectivity issues, rather, it just doesn't seem to work, it leaves the user guessing.
Bottom line is that a great many issues with using the Rewards app is in fact due to connection speed.