Could you please confirm you have actually copied some ‘text’ in your virtual desktop? Selecting the text, right clicking and "Copy" would be safer than Ctrl+C in the virtual desktop. You can also open a notepad in the virtual desktop and try to paste into it, to ensure there exist some text in your virtual desktop's clipboard.
If you have actually copied some text in the virtual desktop, then open "Get Copied Text" box but nothing appears, I suggest turning on your browser's developer tools and checking the error in the console log. For example, for Chrome, the path to turn on console log is Tools -> Developer tools -> Console.
Btw, what is your local client's OS?
