The Armor Master Archetype from Pathfinder Ultimate Combat is incorrectly removing some armor feats. I believe the issue can be corrected by editing the "data\pathfinder\paizo\roleplaying_game\ultimate_combat\uc_abilities_class.lst" file and changing...
Armor Master KEY:Fighter Archetype ~ ARMOR MASTER CATEGORY:Archetype TYPE:Archetype.FighterArchetype.FighterBravery.FighterWeaponTraining_ALL.FighterArmorTraining_ALL.FighterWeaponTraining1.FighterWeaponTraining2.FighterWeaponTraining3.FighterWeaponTraining4.FighterArmorMastery.FighterWeaponMastery
to...
Armor Master KEY:Fighter Archetype ~ ARMOR MASTER CATEGORY:Archetype TYPE:Archetype.FighterArchetype.FighterBravery.FighterWeaponTraining_ALL.FighterWeaponTraining1.FighterWeaponTraining2.FighterWeaponTraining3.FighterWeaponTraining4.FighterArmorMastery.FighterWeaponMastery
This appears to have already been fixed. No reference to Armor is made in either the 6.2 or 6.3 versions I have in the repo, except the mastery.