I thik this might be a timeout of your browser, check the browser console, it should specifiy the error.
Hello Jeff,
The synchronous MF calls timeout by default after a couple minutes. They don't stop running but users won't see the results if you're displaying a page afterwards.
You can try setting it to run asynchronously in the MF settings, or run it in the background with the Community commons "executeMicroflowInBackground" java action.
Hope this helps