If you're having problems uploading images where they seem to load fine (and they appear in files/gimgs) but then nothing shows up in the admin at the bottom, it's due to MySQL 5.7 having strict mode enabled by default, and it's making the db insertion query in table 'media' fail.
To solve it: mattstauffer.co/blog/…
Well, that's what did it for me. If you can't see your files in files/gimgs then you have a permission problem.