Hello Anders,
If the RadComboBox is not opening a dropdown menu on click this could be caused by a JavaScript error. Please check the browser console and ensure that there are no errors on the page. After the JavaScript errors are resolved the RadComboBox should expand as expected.
If the issue persists would you share your full markup with the related code-behind so everyone that would like to help could have better understanding of your scenario?
Regards,
Viktor Tachev
Telerik
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