I facing exactly this throuble.
To reproduce, pllace on a page this:
- a ribbon with some contents, for example a group with a few buttons as in my page.
- a RadAjaxPanel on the page
- a button and a label within it
- add click handler to button that changes text on label
It seems this will be the minimal set required to reproduce thus bug.
I guess that this is related somehow with that scripts are not allowed directly or limited by browsers in ajax by security reasons.