You are likely seeing an out of memory condition while constructing the synthetic keys.
To check this, open the edit script window, and click Debug. Then click on Limited Load and select a number (say 100) and click run to execute the script. After it has completed (you might get a data loop error), check the data model by clicking Ctrl-T. Now you should be able to see the synthetic keys that QV is constructing.
Logic will get you from a to b. Imagination will take you everywhere. - A Einstein