Does it show that you have a ghost in your inventory? If not, try pulling one from your collections.
If yes, check your keybinds, did it get changed to something else?
Also, idk if you know this buti thi k it happened from ammo savingin pvp. There is a glitch in pvp that let's you carry extra ammo to the next round in survival or elimination, doesn't work in trials. Have more than 2 rounds and pull your ghost at rounds end. That's it. This was found on accident and admittedly used whenever I just wanted an extra shotgun or snipe if I got ammo. I wanna say that it was this action that caused the issue because now when I play comp or survival I always keep extra rounds. (As if my ghost is always out)
No key binding changes that would have caused that issue I think. Just a warlock icarus dash change. I've tried swapping ghosts. If I'm at the tower and try to ghost, it just sends out the scanning wave and then quickly motions as if pulling a ghost and then nothing. I can't orbit from any location. Need to hold down and Launch towers change characters