Merchant Voyage: Lost Shipment

Y'all, I'm struggling with these Lost Shipment quests... I've done 4, and the first 3 times I hit the clues, found the captain's key, found the ship at the end, found the manifest which ends the quest, but when I used the key on the captain's cabin, there was no loot whatsoever. I even switched it up and thought maybe I didn't get any loot inside the captain's cabin because I picked up the manifest first and ended the quest. Having completed one by picking up the manifest first and two more by opening the cabin first, it made no difference. Still no loot. This 4th and final time, there wasn't even a shipwreck at the end. I hit the clues, I picked up the captain's key, I made it to the final destination, but no ship. Just a floating manifest under the birds soaring above. Ended the quest, but still no loot. I've YouTubed these quests... there is supposed to be a massive pile of loot inside the cabin, but after 4 attempts, this is proving to be most frustrating. Anyone know what's going on? Is this a common glitch? I read online that the Lost Shipment quests are the best for boosting your Merchant level, but this has been a total bust. Help?