Just purchased a Raspberry Pi 4B 8GB for tinkering, and downloaded and installed kali-linux-2020.3a-rpi3-nexmon-64.img.xz. No issues until I noticed that bluetooth doesn't appear to be working at all. I did throw the lastest raspbian on it to verify it wasn't a hardware issue, and it isn't, everything worked as expected when I did that.
Is this a known issue with 2020.3a? Can certainly provide much more detail if needed, but figure if it's a "yup, not supported at this time" thing, I don't want to waste everyone's time.
