I used the Personal Asset list to find and go to a docked ship that I hadn’t used for over a year. That ship did not show up in the Hangar of the station where it was stored, while the Personal Assets list clearly listed it as being in that station.
While docked in the station: use the asset list to right click on the missing ship and select “make active”. This will make you board the “invisible” ship that went missing from the hangar.