I am using the STM32F469 on three devices. One device works fine and starts normally after the power is applied. The other two only start operating after the nRST pin is briefing pulled low. There is 3.3V on nRST after powering it up, indicating the power on reset is ok, but the micro fails to start running.
Attaching the STM debugger and checking the MCU core it says it is halted. Clicking run starts the device working.
What could cause the device to power up correctly but not start the program running?