This has been working for a couple of years, but in the past couple of months it doesn’t appear any bluetooth devices are being detected.
I am using USB pass through in Proxmox to a Ubuntu VM running HA in Docker.
Running lsusb in both Ubuntu and the HA container console shows that the Bluetooth USB device is present. However, running hcitool scan in both is not returning any discovered devices.
I think I found the solution to the problem. Sharing in case others hit the same problem.
The Ubuntu 20.04 LTS kernel version 5.4 has somewhat nobbled support for certain bluetooth modules. By upgrading to the HWE stack, this upgraded to a newer kernel and hey presto I can scan for devices
This is the command to run on Ubuntu Server 20.04 LTS