This article describes how to resolve some common issues with the 8x8 desktop phone client.
Try logging out of 8x8, quit the application. Wait a moment or two before logging back in.
If the above doesn't resolve the problem, then proceed as below:
Quit 8x8 and uninstall the application.
Go to Start menu > Settings (cog icon) > Apps
Locate and select 8x8 Work and click Uninstall
Once you have uninstalled the 8x8 client, please download and install the 8x8 client from here: