@Ant: yes I aware of that. It turns out that because the firmware will immediately start to connect to MQTT server when that part is imported, it will stop responding to the rest of the import request. So I am aware of why this is happening. One way to fix this is to require a reboot before enabling MQTT, but I feel probably only a small number of users would encounter this so I decided to leave it as is and let them know the work-around if this happens.