I did run into a few glitches in the game, such as objective markers not appearing in some areas or objectives not activating for a certain amount of time for some reason. (gamerstemple.com)
This is all accomplished without the use of detective mode, guardian vision, or any other overt objective markers. (gameluster.com)
They can also be used as objective markers to show progression once treatment and rehabilitation have been initiated. (sportsinjuryclinic.net)