I also think it's not a kernel issue since bluetoothctl is working and able to find Bluetooth low energy devices.
Bluez Ubuntu 18.04 version with latest focal kernel also results in: hcitool lescan Set scan parameters failed: Input/output error
I also think it's not a kernel issue since bluetoothctl is working and able to find Bluetooth low energy devices.
Bluez Ubuntu 18.04 version with latest focal kernel also results in:
hcitool lescan
Set scan parameters failed: Input/output error