Is anyone else having a hard time with the dews on regular Adventurers?

I logged a ticket about the thief (and possibly archer) problem. Annoying for us questhoes.

and i thought that when you had a "drop quest item" active, you where the only one able to see it even if on a party with other people doing the quest.

No. For example, if you have trouble finding or killing Pianus for Carta's quest, you can just wait outside when some randoms kill it. They will not see the Pianus Scream unless they are also doing the quest, and when they have looted all drops you will be able to snatch the item.