Hello!
I have again ghost ratsnest (air wires that seem to be attached to nothing). I had that in the past, but this time I get the problem again, for a different reason apparently.
Looks like there are some tiny loose track fragments flying around and/or split copper poors can’t make a connection. In Pcbnew use the ‘Edit | Cleanup Tracks & Vias…’ command.
Those are two most common reasons. You can try running DRC and finding the missing connections there. There you can see exactly which items arent’ connected, although it may still be difficult to find them in the board.
The loose track segments can be nasty if they are under pads. You can try turning pads invisible in the Layers Manager -> Items. Then it’s easier to see if a ratsnest line ends to a hidden segment.