Let's follow up this discussion at the Neptune Community
(this forum will be kept in read-only mode)
Problem: Copy and Paste functionality does not work in NAD's JS Editor.
Reason: SAP GUI Patch level and IE11 version.
Solution: Upgrade SAP GUI to the latest Patch level and Internet Explorer to the latest version.
My versions at the moment of writing this post:
and this is my IE11 version: