I've tried to get the Luminescent Seaweed as well and I'm stuck now because for some reason, the Driftwood is not appearing to be harvestable for me anymore. :/ And I remember Driftwood re-spawning for me. I don't know if it was the patch on the 12th or because I started the collection that requires the diftwood to be harvested after the Storm-Meta to get the collectible. But they haven't spawned for the last five days I've been trying to get the collectible and it's kind of frustrating. u_u