Could someone please help me with this? See the screenshot, notice how the last track stands alone as a composition by itself, although it’s actually part of the same composition as the previous two tracks. How can I fix this?
If you are using WORK and PART tags (which Roon and I suggest), you need to change the WORK tag to the exact canonical name for that work from Allmusic.com. And that tag should be exactly the same for all three parts.
It appears the third part, Allegro, has a different work name than the first two parts. Change all three WORK tags, one for each track, to:
Horn Concerto No. 1 in E flat major, Op. 11 (TrV 117)
You may be tempted to borrow names from other internet sources, but for Roon, as of now, only Allmusic’s names count.