On repeated encounter, I've had some Open Crew sloop runs that went down rather weirdly...
Just about every time I either queue for - or open up after starting to host one - I almost instantly get a duo partner.
But in uncommon occasions, there's nobody joining. Either directly from the start, or after the last partner left. Sometimes for even up to 2 hours, nobody joins.
As a host, there's completely no way to tell if there's some error preventing people from joining you. And it is something that I would wish to be fixed, or at least been given some transparency/assistance on, to be able to know why nobody joins an open crew sloop that's been open for 2+ hours while under normal circumstances, they're filled near instantaneously.

