The Multi drop-down only loads multis - presets where two or more agents work together. There are not many multis included in Groove Agent 5 and I’m not sure any of the add-ons add any more. Much of the time you only need a single agent, which is configured using the drop-down I pointed you to.
I like The Songwriter’s, too - it was one of the add-on sets I picked up in the recent 50% off sale.