What are the markers for?
Edited
The markers are simply indicators and can be whatever you want them to be. We use them to mark players we want to target, sleepers or players we want to avoid. You can clear them by clicking the counterclockwise icon on the top right of the app or on the website by clicking the "Markers" tab.
Markers are specific to the team you make them for, so make sure you have that team selected in the team drop down.