After call WiFi.off() can not restart softap and led blink white,Photon-0.8.0.rc3 and 0.8.0.rc5

bool clear_credentials(void)
{
        WiFi.clearCredentials();
                                                                                                          
        has_credentials = false;                                                                          

        if (Particle.connected()) {
                Particle.disconnect();                                                                    
        }
                
        WiFi.off();                                                                                       
                
        wifi_is_on = false;
}       
                
bool turn_on_wifi(void)                                                                                   
{               
        WiFi.on();                                                                                        

        Particle.connect();                                                                               

        wifi_is_on = true;                                                                                
} 

1.WiFi is off, call turn_on_wifi(); function,led blink blue
2.WiFi is on,call clear_credentials(); function to turn off wifi,led blink white
3.WiFi is off,call turn_on_wifi(); function,led blink white and no SoftAP can be found
4.WiFi is off,call clear_credentials(); function to turn off wifi,loop() blocked