Be aware that you may have to select your audio interface in BOTH the GarageBand preferences AND in Mac System Preferences > sound. I noticed that in your second screenshot the GB recording level was at zero. That slider correlates with the slider shown in Mac System Preferences.
Be aware that you may have to select your audio interface in BOTH the GarageBand preferences AND in Mac System Preferences > sound. I noticed that in your second screenshot the GB recording level was at zero. That slider correlates with the slider shown in Mac System Preferences.
Complicated stuff.
Interesting watching the attempt at trouble shooting through this medium.
Glad to see you got it working, this thread was a gold mine of basic suggestions.