When open_basedir is enabled, the mediamanager does _not_ check whether all needed directories (especially the temporary ones) are writeable.
If a temporary uplaod directory is not withing the open_basedir allowed paths or not writeable, NO error message is printed. The page is simply refreshing on upload attempts and nothing else happens.
An appropriate errormessage should be shown ;) Therefore the default directories PHP uses for file uploads should be checked, or if set, the corresponding values from php.ini (e.g. upload_temp_dir) should be checked for the correct permissions.
A fix for that is to set upload_temp_dir to a value withing the open_basedir allowed paths.
My configuration is debian etch, apache2 2.2.3-4+etch4, libapache2-mod-php5: Version: 5.2.0-8+etch10; php5: Version: 5.2.0-8+etch10
I hope this helps fixing that bug :)