By default the mod's balaclava is assigned to the make up body slot. This is the only way I've found that will allow gas masks and helmets to be worn with the balaclava. The downside to this is that whenever you wash your character without removing the balaclava it'll be deleted.

If want to change it back to how it is in vanilla follow the steps below:
Navigate to:
Steam\steamapps\workshop\content\108600\3401134276\mods\Vanilla Gear Expanded\42\media\scripts\clothing

Open VGE_Clothes.txt with notepad, find "Hat_BalaclavaTacticalTEXTURE" below that change BodyLocation = MakeUp_FullFace to Mask

This will stop the balaclava from being deleted when you wash, but it'll no longer be wearable with gas masks and certain helmets.