I saw a video on youtube with a guy who is connecting his Switch 'Joy Cons' to his RetroPI System:
https://www.youtube.com/watch?v=0be28t7gz1U

I'm using the "CSL - V4.0 USB nano Adaptateur Bluetooth DEL Class 4.0" - the Compatibility-List says it should work. (I'm using a separat USB Bluetooth Dongle and already tried to switch to different usb ports)

I'm using the latest version of Recalbox on a Raspberry2.

But it doesn't seems to work on Recalbox. Whenever I try to connect one of them it's tells me that the connection was lost. Is there a good way to debug it? Any logs?

Maybe do you have an idea how to solve that problem.

Thanks for your help!