playing on the PS4 multiplayer. Typically 3 people but I don't think this issue is limited to 3 people.
Whenever you leave a dungeon the game glitches and all but player 1 must leave the game to recover. For hospital and cave the game centers on the base. For the school bus player 2 and 3 disappear off the screen.
Also is there any chance the quests can reset? I lost the ability to get the Sherif and the farmer and so cannot get them without resetting the game