LoraWan Sleep on ESP32

I am using a Heltec Radio ESP32 V2 board, with OLED display for POC. I am stuck.
When is use the function lorawan.sleep I cannot wakeup when a RTC GPIO signal transitions after the timer fires?
It works initially after reset but when my timer fires then goes to sleep it will not wake up with RTC GPIO transition, pin GPIO 12 internal pullup resister input. This does make sense.
Does anyone snow what the issue could be?

My code problem. Was not using the function:
esp_sleep_enable_ext0_wakeup(GPIO_NUM_12, LOW);
before calling lorawan.sleep().