Multi-part Composition Grouping not working on MP3?

On several albums roon finds no multi-part metadata in my files. Maybe it’s just bad luck or coincidence but the pattern I notice is MP3 as I am preparing a small travel library. This is the Harmonia Mundi Cornerstones of Scared Music:

The result is, for example, that even after adding WORK/PART tags I cannot tidy up and indent properly a messy Mozart Requiem on Disc 22:

It is the same thing on an MP3 Naxos Best of Tchaikovsky but in this case I happen to also have the ALAC version on my laptop. Roon doesn’t find the multi-part data on the MP3 version but it does on the ALAC version. Can someone @support please take a closer look?



Hi, @tripleCrotchet, thanks for your report! Could you please share media which is affected by the issue? I will contact you via PM with more details.