I would like to get an MP3's ISRC value to show up in Centova's monthly reports.  I found a Python library called Mutagen that lets me programmatically change an MP3's ID3 tags.  I grabbed a test MP3 and gave it a value for the TSRC (ISRC) tag.   The value shows up in both Mutagen and ffmpeg/libav. 

When I upload this test MP3 to Centova and browse it in the Media Library Centova shows the artist, album, and track title but not the ISRC.   What is the tag Centova is looking for for the ISRC value?