Have experienced this issue before in offline Manager Career mode. After configuring the default Tactic, complete with player instructions, and added a new Tactic with the same formation, a number of squad players were positioned incorrectly, based on the default Tactic. When starting a new career mode save, I now modify the default Tactic completely, then instead of beginning a new Tactic, hit the 'X' button (Xbox controller), and select 'Duplicate' for additional Tactic sheets. Since incorporating this style, the player positioning error has not occurred again, however, must always recheck all Tactic sheets when finished for verification.
Community Manager
