NRF thread role

Hi Nordic engineer:

           When I used examples\multi protocol\ble thread\ble_thread_dyn_mtd_coap_cli, I found that the device could not automatically assign LEADER, Router, and CHILD roles.

                 <info> app: Thread version: OPENTHREAD/20180926-00632-g2279ef61; NRF52840; May 23 2019 20:43:08
                 <info> app: Network name: OpenThread
                 <info> app: Thread interface has been enabled.
                 <info> app: 802.15.4 Channel : 11
                 <info> app: 802.15.4 PAN ID : 0xABCD
                <info> app: Radio mode: : rx-off-when-idle
                <info> app: BLE Thread dynamic MTD CoAP client example started.
                <info> app: State changed! Flags: 0x045F133D Current role: 1

                <info> app: State changed! Flags: 0x00000040 Current role: 1    

 
           When I use this example, Thread3.1.0\examples\thread\simple_coap_client, the device automatically determines the role after 10 seconds of power-on initialization.

           <info> app: Thread version: OPENTHREAD/20180926-00632-g2279ef61; NRF52840; May 23 2019 20:44:20
           <info> app: Network name: OpenThread
           <info> app: Thread interface has been enabled.
          <info> app: 802.15.4 Channel : 11
          <info> app: 802.15.4 PAN ID : 0xABCD
           <info> app: Radio mode: : rx-on-when-idle
          <info> app: State changed! Flags: 0x040F131D Current role: 1

           <info> app: State changed! Flags: 0x027012A5 Current role: 4