How to get Audio monitoring in a mac book pro build in speakers

Works here:

Try these setting in Logic's Preferences/Audio/General Tab

Thank you, Pancenter. I tried this, but it didn't solve the issue. Also, my copy of Logic Pro (10.6.3 trial) does not have two of the dropdowns in your screenshot, as you can see here:

I was able to get monitoring to work by selecting the External instrument plugin when setting up the midi instrument:

Reading up on this, it sounds like an add-on. Is there an upside or a downside to using this?

Still curious why the core functionality isn't working.

Or perhaps this is the way it is supposed to be setup?

Some other screenshots, just in case:

I took the screenshot while playing the instrument so you can see the input being monitored. This track was not using the external instrument plug-in, so I couldn't hear anything through the Scarlett Solo headphones.

I'm assuming these (above) are all set correctly...?

The above appears after I create the External MIDI with the External Instrument plug-in. Is this set correctly?

Thanks for your help!