You do have to remove the regulator from the stove or grill as you can not regulate the pressure twice, bit that would have nothing to do wigh not getting gas to the fitting.
How did you determine you were not getting gas? Did the grill just not light or did you actually verify gas flow or lack of at the QD?
The outside fitting with the lever has a check valve in it and will not deliver gas unless a hose is pugged into it. You can't use your appliance gas hose to check that because the QD connector on the end that plugs into the grill also has a check valve that only opens when you plug it in to something.
Look inside the QD connection and you should see a little tab of some type that can be manually depressed. With the lever on, use a flat blade screwdriver to depress the internal part. You should hear propane escaping and smell it. If you do, you have a compatibility issue between the QD connectors. If you do not smell propane, you'll need to start backtracking.
I'm thinking that the outside gas outlet is connected via a "T" to the gas operated appliance closest to it. GD would not have run a separate piece of black pipe just for that one fitting. Stuff like this is not that hard to troubleshoot, you just have to be methodical about it.