Can't get adb on Macbook to see Pixel C
I have tried a number of USB 3.0 cables with no luck but every high quality USB 2.0 cable I've tried has worked for me. This includes USB 2.0 cables that have a Type C connector (There are many of these on Amazon. I'm currently using an "iOrange" brand cord) as well as traditional micro-usb cables with a Type C adapter ("TechMatte USB-C to Micro USB Adapter").

I'd prefer faster charging and better speeds but this takes care of my debugging needs reliably.