Zoom R24 Logic Pro X / High Sierra Control Surface problem (again)

Here it is, yet another thread. Using an iMac (21.5-inch, mid-2011) running High Sierra (10.13.6), 2.5ghz, 16gb RAM, Logic Pro X 10.4.8 (which I believe is the latest this Mac can run).

Zoom R24 is recognized as an audio interface and can read the inputs with no problem, but it will not be recognized as a Control Surface. I did the usual:

• Updated the R24 to the latest firmware (1.13)
• Installed the latest driver (1.5.0)
• Deleted the com.apple.logic.pro.cs file from the Preferences folder and rebooted.
• Went to Applications -> Logic Pro X -> "Show Package Contents" -> Contents -> MIDI Device Plugins, copied the ZOOM R16_R24Driver.pkg file and changed the .pkg extension to .bundle and rebooted
• Followed the thread https://discussions.apple.com/thread/250866428 - and to be honets, I had a hard time following David's explanation. Specifically: "Now go to control surfaces and you will be able to access all settings for the Mackie you are setting up. In my case, I first had to reroute the input and output port and the input port of the Mackie Hui to what was compatible with my Novation Launchkey 49 ( Launchkey MKII 49 Launchkey In Control, both for the inout and output.) The exclamation mark went away once I changed the ports." How does one reroute the input and output ports?? Seems kind of a vague step to me...
• The gray pot labeled "DIRECT" and "DAW" is turned all the way to "DAW."
• Power switch is set to "OFF," screen sez "AUDIO INTERFACE / Sample Rate / 44.1khz"

But nope. Recognized as an audio interface (I can see the R24's condenser mics registering on inputs 7 and 8), but not as a control surface.

I tried on my MacBookPro running Mojave and it works like a charm (and shows a sample rate of 96khz!) -- didn't even need to copy the driver into the MIDI Device Plugins folder (and I tried removing that in High Sierra but nope).

Uhh....help?