BLE shows HCI no device found on Raspberry 4 - probably broken bluez version 5.55 -> downgrade to 5.50 fixed it for me

[my7ho5]

After installing bluetooth on my Raspberry 4 and trying to pair BLE the Tesla Solar Charger page reported that no HCI device could be found.
Checking with "hciconfig -a" it didn't show me any HCI device on the rpi4 while bluetooth itself was running and "dmesg | grep i blue" showed a device.

Searching for the error I found people were downgrading to 5.50 to fix it. Tried it and it worked in my case. So here shortly what I did:

sudo nano /etc/apt/sources.list
# inserted a new line: deb http://raspbian.raspberrypi.org/raspbian/ buster main contrib non-free rpi
sudo apt update
sudo apt install bluez=5.50-1.2~deb10u5
# rebooted the system and hciconfig -a showed a device, pairing and testing worked
# if you want to keep this version of bluez you can do:
sudo apt-mark hold bluez

[my7ho5]

@pkuehnel fyi and thanks for the super fast fix with BLE!