I am assuming you are referring to the fact that there are no mod slots for the Leather Chest piece. This will be a lengthy answer. Yes, I have seen this before.
To start,
AWKCR requires you to use an Armorsmith or Weaponsmith work bench. Not a normal work bench. They are specifically named that. With these MODs you can become very OP right at the start of the game. It is players choice. Some do not like it because you are cheating. I do it all the time.
With
AWKCR,
UCO and
Freecrafter MODs, you can craft most clothing armor and weapons for free at a Armorsmith or Weaponsmith work bench. Then take that item to its corresponding regular work bench and all the mods you want to it. These MODs bypass the games level and perk requirements.
UCO customizations ONLY appear when crafted by the player at Armorsmith & Weaponsmith workbenches.
#1 If you find an item in the world that you want to add mods to, you must meet the level and perk requirements of the game to do that.
#2 If you craft an item from the chemistry station, clothing armor or weapons, and then try to add mods to them, you may see no mod slots available.
#3 MOD conflicts. If you are using another MOD that does similar functions of any previously mentioned, then they must be compatible with AWKCR to work properly. Make sure you have the most current and up to date versions. Sometimes MOD authorize have stopped supporting a MOD and become incompatible with AWKCR. AWKCR has been managed very well over the years. Not all MODs are.
#4 Some MODs do not list AWKCR in the MOD but still work. Case in point. I have Steampunk Gunslinger Outfit MOD. I craft it at the chem station. There are some mod slots for it but not all of them. I can still wear armor pieces over it, like arms, legs, chest and helmet. Those pieces have all mod slots.
My Load Order
The Number is where it is in my load order, I removed the other MODs I have just to make this easier.
2 AWKCR (Armor and Weapon Keywords Community Resource) All DLC,
standardized framework
3 USO (Unlocked Settlement Objects) Core, settlement items
10 USO (Unlocked Settlement Objects), Season Pass
16 Freemaker (ANDREWCX) Complete Edition, produce items with no material or perk requirements
17 Unlock Ballistic Weave
18 UCO: (Unified Clothing Overhaul), Base Game, for clothing and armor
19 Freecrafter (ANDREWCX) Complete Edition, lets you add mods to clothing, armor weapons
Hope this helps.