Looking at your Administrative permissions screenshot, I don't see an item 'Can manage extensions'. It is between 'Can send mass email' and 'Can manage language packs' in my screenshot.
Therefore I don't think you have the necessary permission, which would explain what you've been seeing.
The fact that you also have Settings showing as ACL_A_ADD_USER and ACL_A_MODS rather than text indicates something is amiss with your permissions setup. Off the top of my head I don't know what to suggest to fix it, I've never encountered that case. Perhaps someone else (support team member) has experience resolving this issue.
Normal people… believe that if it ain’t broke, don’t fix it. Engineers believe that if it ain’t broke, it doesn’t have enough features yet. – Scott Adams