Would love to help, thanks for testing it.
I think I stupidly posted the workflow with both debugging and my server pre-configured. You should be able to type: "indigo server http://YOURHOSTNAME:YOURPORT" then hit enter. Alfred should pop right back up again, with the keyword "indigo" pre-typed, and three options available: Devices, Actions, and Variables.
Alternatively, entering your server into the server.txt will also work.
You will know the plugin is connecting to your Indigo correctly if you hit Devices, and your devices dynamically load into Alfred. If you are getting the querying message, make sure you do not have a "/" at the end of your URL (I plan to fix this, but right now it makes the plugin not work, Indigo is finicky about their URLs).
If you are still stuck, please send me your log.txt in the workflow directory via private message, or email to mikel@mikelamoureux.net