Buried treasure not showing up on map properly in multi-player

So I have a friend running a private server on the new snapshots, and we've both been searching for buried treasure, or had been. It seems to work fine for him, the red X shows up and everything. However, whenever I look at maps I found, they have a white banner instead. I've tried using it to find the treasure, but every time I've torn up shores and found nothing. I'm not 100% sure this is a bug, it might just be me being bad at the game, but since I was able to find it in single-player, no problems, even got the red X, I thought I should mention it just in case. Thank you.