Cannot save any scenes in project

Hey all,

I have a very strange issue with my current Unity Project, whereby I can no longer save any scenes, even new ones.

Any attempt to save a scene results in the following error:

NullReferenceException: Object reference not set to an instance of an object

at UnityEditor.AssetModificationProcessorInternal.CheckArguments (System.Object[] args, System.Reflection.MethodInfo method) [0x00000] in <filename unknown>:0

at UnityEditor.AssetModificationProcessorInternal.OnWillSaveAssets...

Cannot save any scenes in project