A friend and I befriended a galleon crew who didn't exactly know their way around the game in detail. So we stayed on the ship messing around with them and showing them parts of the game that they didn't know about. We just so happened to sink a ship that was carrying the skull of siren song. After I picked up the skull and put it on their ship they were able to equip the quest and sailed us off to the Final Destination. My crewmate and I were not able to see the beacon in the sky nor the mark on the map where the final Island was so our galleon crew had to sail the way. I decided that would be a great idea to use their ignorance and sell the skull for myself before telling them the truth behind this voyage and how the gold is calculated between parties. But when we all boarded the island where Brigsby was at to sell, my sloop crew was not able to see or interact with Brigsby making it impossible for us to sell the skull without traveling halfway across the map back to our ship to vote on the voyage.
So my suggestion is automatic joining on to the skull of siren song Voyage the moment you touch any piece from the voyage.
I'm sure there's a few different situations that will have this problem as well such as, row boating to another ship and taking the skull which you did not know was there in the first place or already being on the final Island for a different voyage and the ship with the skull sinks your ship but you were able to kill the crew and steal the skull. I'm sure there are a few more unlikely but possible scenarios that fall under this problem as well but it is kind of disappointing to run into one of them and miss out on all that gold.
I do have recorded documentation on this event if anybody wants to see it.
