I am trying to use the AttachContent OOTB UI control in an Overlay. During runtime, the UI works as it should. The file browser opens as a pop up and I could choose a file. On submitting the form though, there is no file attached to the case. 

However, the same control works when used outside the overlay, as a part of the normal case flow.

Since this is an OOTB control, I am using it as is with minimal configuration changes.

Product Version: Pega 8.5.1

Browser: Chrome and IE

Is this a known issue? Or I am missing out something?

Thanks in advance!