Most Metadata tags are empty after exporting (to MP3)

I am a rather new user of Audacity and I have a problem with the Metadata tags. After exporting a MP3 file (to MP3) nearly all tags are empty, even when I export directly after opening the file. Only Title, Artist, Album, Year, Genre and Comment are OK, all other tags are empty.
I use the latest version 2.3.0 and Windows 7 Pro.

Was the original file MP3? Exactly what tags are you loosing?

I imported & exported and MP3 and as far as I can tell, the only thing I lost was the artwork.

Audacity WILL loose the artwork, and different formats support different tags/tag formats, so things can get “confused” when converting between formats.

Audacity only supports the tags that are listed in the Metadata editor:

I forgot to mention that I look at that data with ‘Tag&Rename’. The tags that are cleared by Audacity, are Composer, Orig. Artist, Copyright, URL, Encoded by, Lyricst, Original lyricst, Label, Remixed by, Radio station name, etc.

However, if I open an exported file and start exporting again, the Metadata-tags screen is OK (contains still all the tags). So, it seems to be a compatibility problem between Tag&Rename and Audacity.