All of your loadouts that are Tier 2 and Tier 3 have to be marked as PvE and not PvP. You can tell whether it's marked for PvP or PvE by the crossed swords on the left; if they're crossed and the loadout is red, it's a PvP loadout. If they're separate and the loadout is blue, then it's a PvE loadout. There's no functional difference between a PvP loadout and a PvE loadout when it comes to PvE, but in PvP only the marked red loadouts can be swapped to freely during Lockdown, which is why all your Tier 2 and Tier 3 loadouts must be marked as PvE in order to play in Tier 1. You can change it by just clicking the swords.