If a user without the autoreviewer right uploads a new version of a previously reviewed (in a last version) file, but does not edit its description page, the file is in the pending changes state. However, after the file is reviewed (either its latest version or the diff), it remains in the same pending changes state. Although the respective record appears in the review log and the diff between the reviewed and the latest version shows no changes. To overcome this, one only has to unaccept the latest reviewed revision and to re-accept the latest file version. (Probably, these are not the only conditions. As far as I remember, this workaround works not always.) See the file [[ru:Файл:Тест.png]] and its review log: https://ru.wikipedia.org/w/index.php?title=special:log&page=File:Тест.png&hide_review_log=0.