nRF52832 advertising not picked up by certain Androids

[danimalia]

Works on Huawei P20 Lite (Android v9), Samsung J3 (Android v7.1.1), all IOS phones.
Doesn't work on Samsung A50.

Samsung A50 does see the devkit when using the same firmware., could this be hardware related? (custom PCB)

[danimalia]

note - verified on two separate A50s. Have also rebooted in safe mode, and removed all BLE apps. phone still does not detect this nRF. 

[Kenneth]

If it works with the nRF52-DK, but fails on the custom PCB, then I would assume that the 32MHz crystal is marginally out of spec (you might need to tune the capacitors on the crystal). You should use the radio_test in the nRF5 SDK to setup a carrier, then measure the frequency accuracy of the carrier on a spectrum analyzer, the center frequency should be for instance within +-96kHz.

Kenneth