Unable to save any changes.

Our resident DevOps engineer is resigning soon and so I've been set up as the interim DevOps admin until further notice. I was given the system admin role and see all the system admin UI elements. However, whenever I make a change and click save changes, nothing happens, the saving icon spins indefinitely. 

I've noticed this same behaviour when trying to create projects, editing build configurations, checking for updates and even trying to change my account name and time zone.

He doesn't have any of these issues and even made me an account with identical roles to his and I have the same issues in that account as well.

What could be the cause of this?

I should add, I've tried different browsers as well as incognito mode.