This is likely caused by a compatibility issue between the version of Citrix client and your browser / operating system. To resolve it, follow these steps:
  1. Close all processes of Citrix in Windows Task Manager.
  2. Relaunch your web browser.
  3. Configure your browser for Blackbaud Hosting Services.
  4. Log into Blackbaud Hosting Services and click the Hosted application icon.
  5. If issue persists, reinstall the Citrix client.
For more information refer to: