Mac OS X 10.14 Mojave client problems

Hi, I tried everything I could think of, but ran out of ideas, so I thought I'd try here.

I've used VirtualHere server on a Raspberry Pi 3 for a few years and the client on Mac OS X (10.11-10.14). It's always worked great. However, I went to scan for the first time yesterday (after not scanning since January), and it didn't work. The client showed the scanner, and connected to it fine, but it won't show up in any of my Mac apps that it used to work with.

First thing I did was upgrade the VirtualHere server and client apps. This didn't fix. So then I thought maybe my scanner was broken, so I connected it directly to my Mac's USB port, and it didn't show up under System Profiler. So I thought yes, it's broken. But I tried with an old Mac Mini, and the scanner showed up and worked. So I knew my Mac's USB stack was all messed up. I went and got rid of a bunch of old kernel extensions that could mess with USB, such as an old KeyspanUSB kext, and some others. That fixed the USB problem, and now the scanner works when connected directly to my Mac.

However, even after removing the old kexts and reinstalling the VH kext, the scanner doesn't show up on my Mac when connected via VH. System Integrity is off, the kext is allowed in the Security prefs and is loaded and running (according to kextstat.) I've restarted multiple times, etc.

The VH logs show the device is found, connected to, and available.

Is there a way to narrow down the problem to VH, OS X, or the scanner software? Do you have the Mac client that was available in 2019 to see if that works? I don't know what version it was, but it was 4.x something, I believe. Running 10.14.

Thanks!