Solution:
Step1: Disable Antivirus / Firewall / IPv6
Step2: Do cache-clear
Step3: Check date and time is correct or not.
Step4: Check system camera is working properly or not.
Step5: Tell the Center person to connect web cam externally.
Step6: Do learner login. In learner dashboard click on LVRD (refresh button) multiple times.
Step7: Check once, your issue will get solved.
If issue persists, please generate the SOLAR ticket with following details.
Learner Code-(those are facing issue)
Screen shot of the issue-
Detail description.
Updated mobile number.