Mon Sep 24, 2018 12:57 pm
As a first check, take a look at this 5-minute video (which was for Resolve 14, but version 15 uses the same procedure) and make sure you follow every step in the exact order. Probably the most important is that Resolve needs to be shut down first, then you choose your input in the Mac's Sound Preferences. The other important thing to understand is that no input is selected in Resolve by default; you need to set up the input manually using the patch window; this is pretty different from how Mixbus and Garageband handle it, so probably unfamiliar to you although you say up above that you are doing the patching correctly. The video shows you how.
I've had no trouble recording on my Mac when I follow these instructions. I suspect Resolve doesn't play well with all interfaces, though (based on troubles others have reported). If the instructions in the video don't work for you, what interface are you using to get audio into your computer?
Resolve 18 Studio, Mac Pro 3.0 GHz 8-core, 32 gigs RAM, dual AMD D700 GPU.
Audio I/O: Sound Devices USBPre-2