Using git RetroArch version on Raspbian, it’s impossible to bind keyboard keys in the Input menu. It doesn’t work for user inputs, and it doesn’t work for hotkey inputs either. You can select a function (Settings->Input->Input Hotkey Binds->Fast Forward Toggle, for example) but whatever key you press on the keyboard will be ignored. Setting the key manually on the cfg file (to a key that is NOT already bound) does work, however.
Is there any Raspbian user around who could reproduce this issue, please?