That list is a device view, which only happens when a "device" is connected. So *something* is connected. Check that you haven't left something in the connect to folder tweak, which BTW has nothing at all to do with where the calibre library is placed. In particular, you must not put the path to a calibre library in that tweak.
This is what I see when looking at a folder device view and right-clicking on the device icon.
And this is what is at the bottom of the screen on the library view.
If you see something different, please show us the screen captures.