[MacT]

pawn Code:

SetPlayerColor( playerid, COLOR_GREY);
            
            new i;
            foreach(i : Player)
            {
                SetPlayerMarkerForPlayer(i, playerid, 0x808080AA);
            }

pawn Code:

SetPlayerColor( playerid, COLOR_GREY);
{            
new i;
foreach(i : Player)
            {
                SetPlayerMarkerForPlayer(i, playerid, COLOR_GREY);
            }
return 1;
}

You forgot change inside function hex color