RME Fireface 800 not "connecting" to MBP, Mojave [SOLVED]

[stubbsonic]

It's a mid 2012 retina MBP running Mojave (10.14.6), I've installed the correct RME driver. The System Report shows that the device is attached. In the Software/Extensions/FirefaceAudioDriver it shows that it is notarized, but not loaded. Though it says "loadable".

I don't know if the driver is only loaded when a certain condition is met by the connected device (perhaps some kind of handshake?).

I've tried:
disk first aid (there were some errors in the fsroot tree that were corrected, after several attempts).
safe boot
reinstalled driver
installed previous version of driver, tried it, then reinstalled latest driver, tried again
I never got the "allow" option, perhaps because it is an identified developer.
rebuild launch services
reset PRAM
tested on older MBP-- it didn't work with FW-to-TB adapter, but did work when I connected it with a FW400-to-FW800 adapter only.
I ordered a longer FW800 cable-- but that is not likely to be relevant.

At first it was intermittent, where sometimes the audio interface would show up. But since I started troubleshooting it properly, I haven't had it show up.

I don't know if it is a hardware or software issue. If it is hardware, it could either be the FW800-to-TB2 adapter, or the MBP's TB port? If it is software, I have no idea what it would be. It didn't seem to fail as a direct result of installing a driver -- but may be related to other audio things that are installed?

[stubbsonic]

It turned out to be a failed (non-functioning) FW-to-TB adapter. I just bought a new one and am back in business.