Customer has updated their SDK to 2.2.3 on Win7/10 and issue has since not occur. I shall close this case for now.
SDK 2.2.3 on Windows caused very strange errors to occur. LEDs blinking erratically, resets, etc. We think there~s something wrong with the fine timer in this SDK version for Windows.
We finally went back to SDK 2.2.2 on Mac. Now the downloaded code works fine, but the initial problem of about 10% of the boards STOPPING ADVERTISEMENT is back.
How can we solve this problem? It's always the same boards that fail; it's not random. For example, if you have 70 boards and about 7 fail, then if you reset/restart all 70, the same 7 will fail again.
This is not a manufacturing issue, because we have used 4 different manufacturers, and different versions of the PCB layout (which follows your guidelines) and always get the same identical problem.
We need to solve this problem badly!!!!