My apologies for this post being on a thread which is several years old, however this is the closest forum item that I have found which has information about my issue.
We are hosting an asp.net web site within a web control within a windows forms application. When attempting to do a row edit using a GridEditCommandColum element, the ajax controller runs the loadingpanel and executes the code behind. From this point it does not release the ajax control loading panel (the gif in use remains and appears paused) and does not execute the edit mode of the radgrid.
This behavior only presents in the web control from the winforms application and does not appear in Chrome, IE, or Edge.
Any information that you have on this issue would be appreciated.