Minecraft: 1.12.2
Forge: 14.23.5.2860

Mods: 6
Chocolate_Quest_Repoured-1.12.2-2.6.10B
geckolib-forge-1.12.2-3.0.28
ReachFix-1.12.2-1.0.5
HadEnoughItems_1.12.2-4.22.0
QualityTools-1.0.7_for_1.12.2
PotionCore-1.9_for_1.12.2

In the gif above... hopefully it shows, I can't trade for any of the items that this Inquisition Solder has since the armor that I'm offering him has NBT Data them, due to having Quality Tools installed. The Diamond Legs that I offered has a 'Thick' quality and even though it's technically the same item... he won't accept that as a valid trade due to the NBT data that the item has. If I drag the same item from JEI which prevents the item from getting a random quality... then he will accept it without any issues.

Quality Tools allows you to give tools, armor and trinkets, etc a 'quality' which will have some attribute modifiers depending on the quality it has. This can range from gaining/losing Health, Armor, Toughness, Attack Damage, Attack Speed, Movement Speed, etc. This also supports attributes from other mods. The quality gets added when the item enters your inventory/hotbar and because of this there's no possible way to complete the trade without dragging the items from JEI.

Iirc the trades of that trader don't ignore nbt data so it is working as it should.

Also for the record: Two itemstacks are not the same if they have different nbt data.

Yep, just checked. The trades are nbt and metadata sensitive, might be changed at some point

Also, while the issue is structured in a good way, please use the issue template in the future

Possible enhancement: make most trades not-nbt sensitive

I prob should've worded it better with the "technically the same item", my bad. I'm aware that they won't stack if their NBT/Metadata is different from one another. Also will keep that in mind for the issue template in the future.

I kinda have a bit of an RPG-like thing going on in my survival world and Quality Tools grants little buffs/debuffs that can either be helpful... or hinder you in a way which is why I have it added alongside Chocolate Quest.