Tag contents not showing when browsing

[samnorthernlights]

Hi. I have purchased a license for Minimserver 2 and run it on my synology NAS. I have just recently encountered a problem I have never seen before. I’ve been using Minimserver for a few years and the new version is just using the settings I had previously with 0.8.

I tag my albums (all classical) with composer, work and part tags. They have been working fine until now. For some recent albums I tagged when I browse the albums using an app on my iPad or iPhone I find the composer and then look in the Work folder and lots of works are listed but then right at the bottom is a folder “Unknown”. In there I found 7 albums for this composer and the work does not appear, even in the file name. I have checked the tags using MP3tag and they are definitely there. I then checked some other composers and I found the same - albums I tagged a while ago. It seems to happen with composers with quite a few albums.

I’ve never seen this before and can’t think what is causing it. Hoping for some ideas here.