I had a similar problem but it was that it failed to bake at all. Not sure if this would relate to your case or not but…
I have never figured it out any settings that had changed. I uploaded a scene here once and nor could anyone else.
My conclusion was that there is a bug someplace that causes baking to stop working and even when it does it is rather tricky some times.
My solution then is to simply open up a fresh scene and append the object. In the new scene the object bakes fine but in the “corrupt” scene it does not. This was the case in the file I had uploaded some time ago. I could not find what was different other than a fresh scene.
This recently happened so I have started to just do all my baking in another blend as a matter of practice.
You say it is baking black though. In my case it would not bake at all. Not sure if this is related or not.