I have a big problem with the RadHTMLChart. It appears it refuses to render until postback if it follows a RadListView on a page. If I put it on the page anywhere before the RadListView the problem goes away and it renders fine. This is the same for a RadHTMLChart that has no dynamic content on it.
Obviously this isn't much help without the codebehind to load the radlistview items from needdatasource, but it appears to be easy to reproduce, just stick the radhtmlchart before a radlistview on a page.
It's nothing to do with updating as I've tested it without any updatepanel, radajaxpanel or radajaxmanager on the page and it does the same thing.