Best bet is to contact the developer of the app. I think he runs the website where you got the nativeboinc app, if I remember correctly. Unfortunately, my involvement with the Android app is limited to setting up the server to support the app. Neither I nor any of the others at PrimeGrid can provide the kind of support that the author can.
Personally, I ran it once on my son's phone when I set it up. It completed one task successfully and then the others failed for some reason, which sounds similar to what you're describing. Since it wasn't my device, I wasn't in a position to dig deeper into the problem. There are Android devices that are successfully returning results.
My lucky number is 75898524288+1