[Afuris weapon slot bug]

Same thing happened to me - cleared out an additional weapon slot (with 2 free already) so I could pick up the Afuris but still have two slots that are unusable.

[Mysterious Reward are not being recieved by other players]

I've experienced this as well. Everyone will get artifact drops, but only the host of the game will receive blueprints. My suggestion until it's fixed is just to solo the alert missions. At the moment every alert mission only has level 1 enemies so it's easily done and you are always guaranteed your reward.