Hello everyone, thanks for commenting on this thread.
Kelso disappearing when trying to hand keys in after a Manhunt is something we are aware of and is being investigated by our Division team.
Ne3mb0t, thanks for letting us know your experience of handing in this 3rd Faye Lau key. We did find that after turning in a key to Agent Kelso the quest will sometimes remain stuck instead of going to the next checkpoint, requiring the next key and our QA team was able to replicate this.
If anyone can let us know what missions you are having trouble completing specifically, where this happens on the map, and if you have any video clips of this, we can open an investigation into this, thank you.