I've just installed Lubuntu 20.04 on my ASUS Q551L and I have paired my phone with my laptop using the BlueDevil Wizard. When I try to send a file from my phone to my laptop I get a "sending failed" message on my phone. BlueDevil's Bluetooth Send File Wizard shows my phone. There is no panel icon (this would be a sign that the system tray application is active - correct?). I have not yet been able to find a Personal File Sharing Preferences file or application which I've read might be necessary for receiving files to function.
In Discovery, the description for BlueDevil Wizard, BlueDevil Send File and KDE Plasma Desktop - Bluetooth all say,
It contains: . . .A system tray application from where all BlueDevil actions can be done . . . . A daemon which listens to incoming requests, for example to receive files . . .
It pairs devices OK, but I can't figure out how to receive files. Also, I can't find the system tray application (is this also called a widget?)