You'll need to open a case with NetApp support to have them look through the logs. They can then open the bug with engineering given what they find (or don't find, since it isn't happening) in the logs.
SnapCenter supports a REST API, WFA support a REST API (which could probably invoke the SnapCenter API to create your clone). Have you considered automating the cloning task? That way you could invoke the task via the WFA portal or via it's REST API on demand and be assured it would be done correctly, efficently and responsively. I'm not sure about why SnapCenter is creating the export policy but it's simple to automate the removal of it using WFA or API-S.