Jitsi application does not preview video

Hi Jitsi Experts

I have installed Jitsi app(2.10.5550) on two Linux PC (Ubuntu 16.04) and established the jitsi connection.

Now we are seeing a strange issue with one of the linux PC, even though jitsi detected webcam and transmitting video to peer, but locally preview is showing as black screen.

Am I missing any configuration.