Spine is not showing you the filesystem. It shows you the image files it finds. If a folder has no image files, it does not appear in the tree under the Images node. That is why your new folder doesn't appear.
When you make a copy, it appears correctly. When you rename it to Head it should not disappear like your video shows. We've reproduce the issue easily, renaming any folder causes it to disappear. Not sure how we've missed that, and had no reports until now. 👀 We've fixed it in 4.2.40. Thanks for letting us know!
Generally if files or folders are not appearing, clicking Refresh is enough. Restarting Spine should not be necessary. Reinstalling Spine will not do anything more than restarting it would.
