Facing Issue with Video calling


We have integrated MobileRTC Framework for Video calling. We are facing issue at very first time when we start video calling (at the time of getting permission for camera & microphone) video should be start just after taking access for Camera and microphone. but only black screen is appeared.
We have develop app in Swift 3.2 with Xcode 9.2
from second time it works fine. 
Please assist as soon as possible. its Urgent as we already published app on Store. 


Is the video not loading on the first try but then loading on subsequent reloads? 


Please share any logs you have that will help with troubleshooting. 


Please tell us the version of MobileRTC which you used, I think the MobileRTC is not latest.