The delete itself in Sunami and Nostria is basically the same, has to either be that the delete not being sent to all relays that the music was on, or perhaps some relays have issues with "k" tag on delete events? @Sunami doesn't set "k" tag, but the NIP-09 says it "SHOULD" do so, but I highly doubt that is the reason.

Also if you delete a music track, for any existing user that have the music cached, they must open each track individually and then it will disappear from their album.

I'll implement some logic in the future sometime where it will go through all cached music and attempt to retrieve any delete events that exists for them and remove from cache.

There is still a a couple tracks that does not disappear fully Henrik, they appear in both Sunami and Nostria, I will send the IDs to you in a DM so you can delete those too.

If some of your delete tracks still is listed in Nostria on your device, just open their details page, wait a few seconds while it gets the delete event and this should appear, and it will be gone. Understand this is frustrating and slow process to clean up locally, will get better in the future.