Not sure on which part the issue is underlying, but sadly the Pocket Jukebox doesnt work with https://modrinth.com/mod/url-music-discs. It does accept the disc, but sadly does not play it.
If its not on your side; sorry for false report

Edit: turns out these mods use a completely different logic for music discs. So it's completely on their side, nothing AA can do

Same problem with the Etched mod (https://www.curseforge.com/minecraft/mc-mods/etched), except it doesn't even accept the disc

@hyperdotbat if you still need it, the etched mod has a boombox item, which basically does the same thing as pocket jukebox, except it also accepts it's own mod's url discs