Not specifically a desktop issue, but it's happening on my desktop so close enough.

My work uses Citrix Workspace and in recent months it's taken on this grey overlay that isn't something I've encountered before - see the screenshot below from the Outlook web app from within Workspace. I used the web app to email my work's service desk - who responded by telling me how to change colour schemes in MS Office.

This problem afflicts all applications I use in Workspace, be it web browser or MS Excel.

Thanks in advance for any help.