Hours of trying to debug this, I've setup as simple an example as possible by hardcoding my URL parameters for a REST query, for example "client_id=12345".
When I click "Preview", everything looks fine, query is successful and the response is what it should be. It works.
When I click "Run" the query does not work and returns a server error because for some reason client_id="undefined".
I don't get it
ps. I does the same thing if I put the query parameter into a text field instead of just putting it directly into the interface.