I'm not a Mac user but here goes... I'm a bit confused about your post - do you not see any uploads at all per session? Have you added files to your Public Shared list, so that other people can download from you? Is LW showing you as behind a firewall (in LW Tools > Advanced Tools)?

In LW's preferences > Advanced > Transfers do you have 'clear uploads from list when finished' ticked? If so, untick that box > ok. Now all uploads per session will be shown.
Or are you seeing an error message with attempted uploads? I can't remember all the upload error messages across the different versions, but some are 'upload limit reached', 'unable to complete upload', 'unable to upload no error'.

And are you having trouble with downloads as well?? What happens when downloads fail (download stalls, won't connect etc)? Are you checking files with Bitzi before download (control+click > View File info > More File Info)? What file types won't download? Is it all files or just occasionally?

Is your LW properly connected (all green/blue connection bars)?

Codecs are needed to view downloaded files on a media player. Doesn't sound like that's your problem