The title of this thread pretty much explains it all. In an already toxic game, these missions basically killed the game mode for anyone after the first couple days.
You'll normally get one person (sometimes more) that will afk or "feed" if they don't get their way in champ select. If the player doesn't get everyone to have however many augments they want....this person will either afk, "feed" or troll the team until you either surrender or get defeated.
Either fix the missions by changing them entirely OR just remove missions entirely. I get that Riot wants people to try harder difficulties and/or hardmodes but with the state of the player base this is entirely unplayable now.
I would suggest removing the missions as the mode itself is rather fun to grind if the players just play whatever they feel like.