We have had problems with RadAsyncUpload in IE11 where it will give a yellow dot and freezes when uploading files. This has been happening since our users started using IE11 (on Windows 8.1). Previously they used 10 without issue.
This does not happen if we direct them to Chrome. The only way around it we have found is to turn off the FileApi Module for IE. We do utilize drag and drop so when that module is disable that functionality is lost. I am using the latest version of the controls 2016 Q1.
I also tried to emulate IE10, but that does NOT solve the issue. We run with ie=edge meta tag.
The problem is intermittent and I have not been able to reproduce it myself. I have seen some similar threads on problems like this including this one: http://www.telerik.com/forums/radasyncupload-1fc6f6296712
Is there any kind of known issue or workaround? It is difficult to troubleshoot given the intermittent nature.