Also you might get something like
fatal: Pathspec ‘some.file.name.goes.here’ is in submodule ‘some/folder/name’
Also you might notice, if you commit and pushed, only some skeleton of the of the folder structure without the actual files would be committed.
The root of the problem is the folder you are trying to add is tracked under git itself.
This would confuse git and would rather leave it up to you.
the fix
First go ahead and remove the .git folder in the new directory
sudo rm -rf /path/to/new/folder/.git
Then clear the cache from git memory of the new folder
git rm -r --cache /path/to/new/folder
Then when you do the
git status
you will see all the new files being listed and you can commit that.