Using IN operator in Nintex Queries

Has anyone used the IN operator in Nintex queries? It's not available in the operator dropdowns in Query List actions. 

When I try to use the CAML editor and manually form the query using IN operator, I can't RUN or SAVE the action. It just hangs the browser and I have to close it with task manager.

 Here is the link for the IN operator MSDN article: http://msdn.microsoft.com/en-us/library/office/ff625761(v=office.14).aspx 

Any Ideas? 

Surya