This is a very odd issue indeed. It likely points to a javascript error. This could be because of some custom plugin, or code modification, or something on the web server interferring. Even more odd that it works in some browsers and not others. Perhaps some browsers handle the javascript errors different.
I'd inspect the page in your browser, reload and check the Network > XHR (In Chrome anyway) and see if the widgets are being returned, and if there are any errors.