Camera turning doesn't work anymore

Hello,

I recently opened my project again when suddenly turning the camera in my project doesn’t work. Instead of rotating/turning when the mouse is moved, the camera stays static. The only way for the camera to move is if I have the left or right mouse button clicked down and then move the mouse.

I have been using the First Person Shooter Blueprint setup in 4.7.3. I have not updated to 4.7.3 recently. I did not change anything in the project, I simply opened it up and this problem presented itself.

Quick update:
Tried adding another first person character and controller into the project, that too did not work.