What should I do with duplicate cosmetic items that can't be sold on the Item Market? (Specifically thinking of Steam collaborative items that are already bound to my account.)
Converse with fellow players
It appears now, though I'm not sure if it was from completing an expedition quest for the first time or completing A Case of Murder III that did it. Though it does seem odd that A Case of Murder V is available regardless if the latter is the case.
For the Mission Bingo, one of the requirements is to complete one of Lavere's Client Orders called A Case of Murder IV. However, when viewing Lavere's Client Orders, this one doesn't exist. There's A Case of Murder I through V with no IV in sight. Is there something I'm missing?