RUI3 v4.2.3 STM32 — Boot loop when LoRaWAN API (set/join) called in setup() — official OTAA example also affected

[oharis99-Embedded]

Hardware: RAK3272S (WisDuo Breakout Board, Ver. C)
BSP: RAKwireless RUI STM32 v4.2.3
Arduino IDE: [your version]
Issue: Boot loop when any LoRaWAN API is called in setup()

Tested with:

• Official LoRaWan_OTAA example (unmodified except band=IN865, credentials)
• Also boot loops on the official example

Serial output:
RAK OTAA Test — IN865

[immediate reboot, repeats indefinitely]

The NWM guard never prints "Switching to LoRaWAN" — device is already
in LoRaWAN mode (AT+NWM=1 confirmed via AT commands). Reboot is
triggered by appeui/appkey/deui/band set() calls.