I am having the same problem with 2.3.3
I set up another WP with plugins with no problems.
I have added several plugins to my plugins folder but they do not show up in the plugin management page or the plugin editor page. When I look at the plugin file folder using my control panel, they are there. Apparently the plugin management folder does not update?
The permissions are the same as “Hello Dolly” and “Akismet” which do show up.
I am on a rented space sever with a full control panel.