Hey I did some digging and you can only get the power armor if you have the automatron DLC so this can only happen if you bought the dlc cuz it’s a quest
pull up the menu, on ps4 its the touchpad, go to vehicles, request personal aircraft, keep pressing right button till you see your hydra and select it.
i just bought the hydra and it does not show for me in the interaction menu but when i try to buy another hydra it says i already own one what do i do ???