Why do scriptableobjects get locked in inspector?

I have been developing with unity for a while and just began using scriptable objects.

A constant problem I have is their fields turning grey in the inspector. If I make a new SOs from the same source file I can edit them but the older ones stay inactive. This seems to happen pretty randomly and I havn’t changed the .cs file of the scriptable object in between.

Anyway to unlock them? I saw advice that turning debug on would open the object up but this doesn’t happen.

Not sure what you mean here. Any screenshot?

Just deleted my old scriptableobjects that didn’t work. I will post a screenshot when one inactivates again.

The inspector just turn grey when the object is selected and it can no longer be edited.