I don't know if this is related and I'm sorry if it's not. I came to this thread looking to see if anyone else was noticing buttons missing.
I just upgraded to v2.918 (internal). I have a form where the user can't see the button image but they can mouse over and activate it. This is purely a rendering issue. Using Firebug (FFv15.0.1) we're seeing the WebResource call from the style is failing for that specific session:
The failed call is on a PC in the same office with IIS, where the URL to the site is going resolving from the internet (www.corp.com/page). From another PC, out of the network, with the same browser version, I do see the button. But I did see this happen while working in VS too. I'm told this is a flaky issue, doesn't always happen. Of course we can't have buttons randomly disappearing.
It probably doesn't matter but my code is as follows:
TableRow row =
TableCell cell =
RadButton b =
"Click for report : "
I'm re-uploading the RadControls assemblies to IIS and will report back here as to whether or not the problem persists.