What you can do at this point to debug the camera in-game is:
- Add a tick method to print the following info:
- CameraComponent is valid.
- Camera view itself is correct.
- CameraComponent absolute location is correct and it (and its spring arm) move correctly, relative to the character.
- Spring arm length is correct.
Movement should definitely be movable on a character. That you can not move your character would be another problem if this happens in movable mobility mode.