Spirit System

You can try the latest driver from manufacturer:
https://www.silabs.com/documents/public ... Driver.zip

We have many users on High Sierra that reported success. So I believe it will work also in your case.

Regarding the device, it should be directly in "/dev" drirectory.

Hello Omegatron. The issue turns out to be that the Mac version of the Spirit app is not recognizing and is not connecting to the Spirit units, even the Spirit units that do not have the telemetry enabled. The Spirit units will connect to the Windows version of the Spirit app via Parallels on the same Mac computer. So it looks like the issue is related to the Mac version of the Spirit app and or the drivers.

Actually the problem is not with Spirit units, but the USB interface. With Wifi-Link it would work for sure. Basically you can find when it will work even without connected unit by checking for presence of the device in your OSX. If it is missing, it can't work (because it has no way how it could communicate with the unit).
Unfortunately High Sierra broke the compatibility of the driver. So other driver is required there.

So if I understand it correctly, the issue has to do with the High Sierra Mac operating system, that there are currently no drivers available to make the Mac Spirit app connect to the Spirit unit via the USB adapter? If this is the case, it seems that there is nothing to do for now except wait for compatible driver?

No, the driver is available - actually one that is linked in the manual and you have tried should work with High Sierra (at least it worked for all people that tried it).
So solution is there already. Hopefully the latest driver will work for you. If it will not work, we will perform update on our Mac to test it.
Since we are afraid about update (it could break our building station) we have not did it yet.

In that case, what is the solution to my issue? How do I get the Mac Spirit app to recognize the Spirit units?

I called AppleCare. Apple told me that the Mac computer and the USB ports are working properly. Apple told me to get help from the app developer.

Please try to download and install this driver:
https://www.silabs.com/documents/public ... Driver.zip

If it will not work, then we will check what could be wrong. The problem is just in software, they changed few internal libraries. Unfortunately from time to time things like this are happening during major OS updates.

Still does not work.

Thank you for the message. We will try to find the reason.

What is a good next step?