I have inspected the issue by testing RadAsyncUpload locally and on our online demo(where the settings of the control are almost the same as the ones you pointed and with RadAjaxPanel) but unfortunately could not achieve the same error. Here is a video
of my test. Would you please review it and let me know if I am not testing properly or I have to add something else to observe the same issue?
I am attaching a sample web page with the isolated demo. Would you please let me now if the same behavior van be observed there as well?
the Telerik team
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