Wanderers Refuge glitch

@iceashw A lot of the time I find them spawning on the east side just off the top of the island down on the shelf where the grave markers and the skeleton of the grave robber are. Also did you check the caverns on the island? Perhaps they were underground - I haven't run into that at Wanderer's (but also haven't had a lot of skull bounties there either of late) but have many times over at Lone Cove, hearing the music above but not finding them because they were in the cave below me.

Sometimes there is a glitch with OoS-like missions where you’ll hear the music but no skeletons appear. Sailing away and coming back or going to the Ferry of the Damned and respawning typically fixes it

And to add to @promotordj comment sometimes they spawn inside of rock formations on the island. If you cannot get them to respawn by sailing away and coming back then you can sometimes locate the rock formation they are trapped in by following the music then swing at the rocks to try and kill them - gunpowder keg also works. I had this happen once on one of the small islands in the upper NE corner of the map once and was able to get them by slashing at the rocks. Might not be as easy to locate them on an island as big as Wanderer's Refuge though.