It's not very clear what your problem is.
If you only mean the loader is not loading *all* luggage from the cart, that's not obviously a "bug" or something that requires a fix and this has been explained so many times on the forum too.
The animation is fixed and its made to load 4 bags from each cart, and it works like this, because that's the only feasible way to make this kind of animation in the FSX/P3D engine, which is very limited regarding human animations. So yes, you see additional bags not loaded on Boarding and carts not entirely empty on Deboarding, because some bags are fixed in the cart and not part of the animation.
Just pretend those extra bags are coming from another flight, and the cart is just making a round trip to serve both. Bags have a tag with the flight number, so they shouldn't be mixed up.
Or, just pretend that, AS IN REAL LIFE, the handlers are a bit confused, so the bags are mixing up with another flight, and might eventually get lost...isn't GSX realistic ? Reality is not always "perfect".