Do you think you can take of your keep-on-failing boards and load it with the hello sensor app? This may give some clues on the
health of the hardware and perhaps layout.
We have tried that (as part of a Case we have opened). I posted on the Forum to try to get some community feedback as well.
The result of that test seems to show that the hello_sensor application does not fail.
But, the most difficult part of the problem is that some ICs fail consistently, while others do not fail at all, even when loaded with the same code, and run for several days. So, I don't believe the failure is only related to the code. There seems to be some relationship between the code and the hardware which is popping up intermittently.
I was especially intrigued by the observation in the "Advertisement seems to be flakey" post that the problem was traced to a faulty Tag. The poster replaced the Tag and the problem did not reappear.
You meant to say that on those bad boards/parts, the hello sensor app did not fail?
If you have a hunch that the IC could be the issue here, then please discuss this with the engineer who is looking into your case. We usually may need to do a FA for such cases.