I heard I should rebuild the database on my PS4, so I did, while my external drive was plugged in. Now, none of the games on that drive are in my games folder. However, if I go to storage -> external drive -> applications, all the games are still on the disk. Is there a way to access the games without manually reinstalling them all?
Edit: so, I unplugged the external drive and rebuilt the database, then plugged it in and waited turned it on. After waiting for quite a while on the home page, my external drive games one by one gradually popped up. I don't know if the second database rebuild was necessary and I just needed to wait, but issue is solved.