My roster did not lock at the end of the join/preview period but sometime in the 30 min after that. I specifically waited until the Player Lock period was over (4:00 P.M. for me) to move some mods for a raid and I moved them back 30 min later. Now I have several partially modded characters and several more poorly modded characters locked for GA which makes me not even want to bother participating as these mod loadout changes will likely cost me the match. When exactly does roster lock occur? I would like to avoid this issue in the future and unfortunately GA starts when my guild is usually 1 hour into our HSTR.