STM32WLE5CC join accept not seen

[SLevi.1]

I'm using a STM32WLE5cc inside a RAK3172 (TCXO) module on a custom board. I have custom firmware developed in the STMCube IDE. So, my join request is seen on the gateway, and the gateway sees a join accept from the server. Unfortunately the joined event is not seen on the STM. I'm using the endpoint template as a framework.

What is the best procedure to track down where the fault lies?

[SLevi.1]

Even though the interrupts for radio rx & preamble are being setup, they are never firing. Radio tx fires ok, so the interrupt handler is ok.