Same with me, now happened twice.
I have Nuendo Live 1, and Nuendo Live 2. Using Yamaha TF-Rack
Nuendo Live 1 work fine with Mojave
Nuendo Live 2 did not receiving any audio input with Mojave, so I go back with Nuendo Live 1
Now I’m upgrading to Catalina, and now Nuendo Live 1 also not working, no audio input