I purchased JRiver Media Center 30 64-bit Master License and I installed and licensed it on Zorin OS 16.1 Pro 64-bit based on the older Ubuntu 20.04.3 64-bit LTS GNU/Linux distribution. I have downloaded several newer music albums in the FLAC format and then I transcoded them into Monkey's Audio at the insane compression level and I finally transcoded them to the Opus lossy audio codec at 128.0 kbps bit rate. I imported the Opus music albums that I acquired today into Media Center 30 and it showed up properly and the Opus audio tracks were tagged properly. With previous JRiver Media Center versions such as 29 and earlier, the Opus music albums and tracks could be imported, but they showed up in a long list under various artists and the tags were not properly sorted through. I had to resort to using Musicbrainz Picard to cluster artists and music albums and tag and save those tags beforehand and then I could import them into JRiver Media Center 29 64-bit Master License or earlier versions with proper tagging support.
I thought to share this observation for some people that have repeatedly asked the JRiver developers to support the Opus lossy audio codec including tagging support in previous versions and I want to share with other JRiver customers that it seems that this has been fixed with JRiver Media Center 30 64-bit Master License and this too includes GNU/Linux support as well.
I usually create smart playlists and upload my Monkey's Audio insane audio tracks to JRiver Cloud Play and then I delete all copies of lossless music and keep my Opus lossy audio codec music albums and tracks. I shall continue paying for each major JRiver Media Center version when each one is available for pre-order at a special discounted upgrade price in the foreseeable future. Thank you to the JRiver team for updating Media Center 30 so that Opus lossy audio tracks are imported properly including tagging support. For what it is worth, I use the free and open source Fre-AC or Free Audio Converter to transcode from FLAC to Monkey's Audio and finally to Opus. It seems that I do not need Musicbrainz Picard, but I shall keep it.