When editing a Condition that has a large number of Expressions, the URL generated for editing these becomes too large for the URL scope (see example below).
Tried increasing the large_client_header_buffers directive in the nginx.conf but that only partly solved the issue + it doesn't scale well if this happens to other clients.
Dom and I had a brief discussion on this and it was agreed the Rules Engine Condition Editor would need to be refactored to pre-post the values/state using a form submission which in turn stores the values in flash memory to be accessed by the subsequent AJAX modal/iFrame request.
This approach has been implemented previously for the Widget Rich Editor also. So this could be used as a reference point for the implementation.