Once an external HF field is detected, when a first byte is received, then NFC IRQ is called non-stop.
But none of the conditions in nrfx_nfct_irq_handler() is met so the handler does nothing and there is no chance to get called from a registered callback.
Side effect is that main loop cannot run, button IRQs are called but button processing in main loop is not called, etc.
So one of the side effects is that bsp_wdt_feed() is not called.
Current workaround is to call bsp_wdt_feed() at the end of nRF SDK nrfx_nfct.c nrfx_nfct_irq_handler()
I suspect the hack of the NFC state machine done in nfc_14a.c nfc_tag_14a_event_callback() case NRFX_NFCT_EVT_FIELD_DETECTED
to get access to the anticollision phase is breaking sth in the SDK state machine, NFC IRQ should be called only on real change (field drop, cmd received,...)
dxl