The issue with the skirmisher torsos is that they are set to be usable with any armor which isn't something you can do with the torso slot.

The fix is just going into the XcomContent.ini in the mod's config folder and changing any bAnyArmor=true in the torso sections into ArmorTemplate="PlatedSkirmisherArmor"
This will make it only usable with plated armor, but it work break things anymore

Remember to also do the female ones, which are in their own grouping in the config

Alternatively, delete the skirmisher torso sections in XcomContent.ini and paste in the following -
NOTE: Male and female parts are in different groups so you should have two different section you paste over

-MALE

;Torso
+BodyPartTemplateConfig=(PartType="Torso", DLCName="HeroGear", TemplateName="Skirmisher_Underlay_M", ArchetypeName="WoTC_HeroGear_SkirmisherUnderlay.Archetypes.ARC_Skirmisher_Underlay_Torso_M", Gender=eGender_Male, bVeteran=false, ArmorTemplate="PlatedSkirmisherArmor", CharacterTemplate="SkirmisherSoldier")

+BodyPartTemplateConfig=(PartType="Torso", DLCName="HeroGear", TemplateName="Skirmisher_Full_Plate_Torso_M", ArchetypeName="WoTC_HeroGear_Skirmisher_PlatedTorso.Archetypes.ARC_Skirmisher_Full_Plated_Torso_M", Gender=eGender_Male, bVeteran=false, ArmorTemplate="PlatedSkirmisherArmor", CharacterTemplate="SkirmisherSoldier")
+BodyPartTemplateConfig=(PartType="Torso", DLCName="HeroGear", TemplateName="Skirmisher_Full_Plate_Torso_ChestPaint_M", ArchetypeName="WoTC_HeroGear_Skirmisher_PlatedTorso.Archetypes.ARC_Skirmisher_Full_Plated_Torso_ChestPaint_M", Gender=eGender_Male, bVeteran=false, ArmorTemplate="PlatedSkirmisherArmor", CharacterTemplate="SkirmisherSoldier")
+BodyPartTemplateConfig=(PartType="Torso", DLCName="HeroGear", TemplateName="Skirmisher_Full_Plate_Torso_PaintA_M", ArchetypeName="WoTC_HeroGear_Skirmisher_PlatedTorso.Archetypes.ARC_Skirmisher_Full_Plated_Torso_PaintA_M", Gender=eGender_Male, bVeteran=false, ArmorTemplate="PlatedSkirmisherArmor", CharacterTemplate="SkirmisherSoldier")
+BodyPartTemplateConfig=(PartType="Torso", DLCName="HeroGear", TemplateName="Skirmisher_Full_Plate_Torso_Scratch_M", ArchetypeName="WoTC_HeroGear_Skirmisher_PlatedTorso.Archetypes.ARC_Skirmisher_Full_Plated_Torso_Scratch_M", Gender=eGender_Male, bVeteran=false, ArmorTemplate="PlatedSkirmisherArmor", CharacterTemplate="SkirmisherSoldier")

+BodyPartTemplateConfig=(PartType="Torso", DLCName="HeroGear", TemplateName="Skirmisher_Veteran_Plate_Torso_M", ArchetypeName="WoTC_HeroGear_Skirmisher_VeteranTorso.Archetypes.ARC_Skirmisher_Plated_Veteran_Torso_M", Gender=eGender_Male, bVeteran=false, ArmorTemplate="PlatedSkirmisherArmor", CharacterTemplate="SkirmisherSoldier")



-FEMALE

;Torso

+BodyPartTemplateConfig=(PartType="Torso", DLCName="HeroGear", TemplateName="Skirmisher_Underlay_F", ArchetypeName="WoTC_HeroGear_SkirmisherUnderlay.Archetypes.ARC_Skirmisher_Underlay_Torso_F", Gender=eGender_Female, bVeteran=false, ArmorTemplate="PlatedSkirmisherArmor", CharacterTemplate="SkirmisherSoldier")

+BodyPartTemplateConfig=(PartType="Torso", DLCName="HeroGear", TemplateName="Skirmisher_Full_Plate_Torso_F", ArchetypeName="WoTC_HeroGear_Skirmisher_PlatedTorso.Archetypes.ARC_Skirmisher_Full_Plated_Torso_F", Gender=eGender_Female, bVeteran=false, ArmorTemplate="PlatedSkirmisherArmor", CharacterTemplate="SkirmisherSoldier")
+BodyPartTemplateConfig=(PartType="Torso", DLCName="HeroGear", TemplateName="Skirmisher_Full_Plate_Torso_ChestPaint_F", ArchetypeName="WoTC_HeroGear_Skirmisher_PlatedTorso.Archetypes.ARC_Skirmisher_Full_Plated_Torso_ChestPaint_F", Gender=eGender_Female, bVeteran=false, ArmorTemplate="PlatedSkirmisherArmor", CharacterTemplate="SkirmisherSoldier")
+BodyPartTemplateConfig=(PartType="Torso", DLCName="HeroGear", TemplateName="Skirmisher_Full_Plate_Torso_PaintA_F", ArchetypeName="WoTC_HeroGear_Skirmisher_PlatedTorso.Archetypes.ARC_Skirmisher_Full_Plated_Torso_PaintA_F", Gender=eGender_Female, bVeteran=false, ArmorTemplate="PlatedSkirmisherArmor", CharacterTemplate="SkirmisherSoldier")
+BodyPartTemplateConfig=(PartType="Torso", DLCName="HeroGear", TemplateName="Skirmisher_Full_Plate_Torso_Scratch_F", ArchetypeName="WoTC_HeroGear_Skirmisher_PlatedTorso.Archetypes.ARC_Skirmisher_Full_Plated_Torso_Scratch_F", Gender=eGender_Female, bVeteran=false, ArmorTemplate="PlatedSkirmisherArmor", CharacterTemplate="SkirmisherSoldier")

+BodyPartTemplateConfig=(PartType="Torso", DLCName="HeroGear", TemplateName="Skirmisher_Veteran_Plate_Torso_F", ArchetypeName="WoTC_HeroGear_Skirmisher_VeteranTorso.Archetypes.ARC_Skirmisher_Plated_Veteran_Torso_F", Gender=eGender_Female, bVeteran=false, ArmorTemplate="PlatedSkirmisherArmor", CharacterTemplate="SkirmisherSoldier")