I still cannot find it there, I am using the last version 5.5.1, normally this should appear under Awaiting Installation but it is not there. I can see it in older version of concrete 5. I have tried different downloaded themes but they don't work when uploaded. You can install free themes from the market place but downloaded or self package theme cannot be found. A bit weird. Maybe you can only install through the market place or in the theme folder. Can someone confirm this.
Theme downloaded from concrete5.org does not show also. I have reinstalled cms on another hosting, same problem and also tried a paid theme, also did not show up. But installing theme through market place works well.
Can you take a screenshot or write out your folder structure starting with /packages/
My theory is that the directory structure is incorrect, and thus concrete5 is not seeing the package.
Normal installation would be something like /packages/cooltheme/themes/cooltheme
Sometimes when you download and extract a package, it creates an 'extra' top level folder. If you upload that to /packages, you'd end up with a structure like /packages/cooltheme/cooltheme/themes/cooltheme which will not work.