Please try the following:
- Uninstall Test Studio
- Check Firefox for remaining Telerik add-ons - if any please remove them manually
- Check the product installation folder (default is Program Files x86/Telerik/Test Studio) - if any files have been modified the installer will keep them there; please delete the folder
- Install the latest build again.
If you still experience the problem please check for any additional add-ons - we have seen conflicts with 3rd part add-ons in the past. If so you can try disabling each add-on (and restarting Firefox) one by one to see which is causing the problem.
As to the screenshot in our documentation - that seems like the old name of the add-on, which we will fix. Thanks for pointing that out!