When I try to insert an image into an ASPxHTMLEditor, using the "insert image" tool button, it just hangs with the word "Loading" displayed and goes nowhere. This is only happening with the web page on a production server, it works fine in a development environment. We already know that user impersonation exists for that page.
This could happen if you performed the "Publish Web Site" command in Visual Studio when deploying your web application.
To solve your problem, please check if the following code-behind files exists on the production server (~/DevExpress/ASPxHtmlEditorForms/):
If these code-behind files don't exist, then copy them to the ~/DevExpress/ASPxHtmlEditorForms/ directory on the production server.