Im playing on the latest 2.1 experimental build, and I noticed that wagons will only be filled up to the maximum normal quality of the wagons, instead of scaling with the quality wagon's storage capacity. if this is intended behavior I apologize for posting about this lol
(Bob's mods + Adjustable Quality)

Try going into the settings and set the default stack size. I’ll be honest I haven’t tested quality differences, but see if that helps you out. I’ve never done a play through long enough to get to quality. I originally built this month for pys run

If you can share with me a copy of your save, and you don’t mind me taking a look, I might be able to see what you’re running into and run it through my harness

Are you referring to fluid wagons only or cargo wagons only, or both?

Its both, and https://drive.google.com/file/d/1svlIuJ287wOviikQGkWUOwYa34pP7GHs/view?usp=sharing

Have you tried hard coating the requester stack size and the fluid wagon default size in the per map settings in the mod not from the menu or the Combinator menu?

Do you run mixed sized trains or are all of your cargo wagon trains the same size as in do you have some quality wagons and some non-quality wagons is that a thing?

I run all my wagons at legendary, and almost everyone would probably run wagons at 1 quality step or another...I have not tried modifying the requester stack size in the code itself, but, the mod does know about the default stack size of the Tier 3 wagons being 80 stacks and 100k units respectfully

Try these three settings first (image below). Deliveries are sized off the request, not the wagon — so bigger wagons only matter if the request is big enough to need them. The defaults (40 stacks ≈ one normal cargo wagon, 50K fluid ≈ two fluid wagons) were tuned for small early trains; override per-stop at the RLD combinator, or globally under Settings → Mod settings → Map (takes effect immediately). One caution: don't raise a threshold above what your largest train can carry, or that stop will stop dispatching entirely.

Change the settings built into the mod overrides screen. See this image below for a reference as an example.
https://imgur.com/a/o0bQPWj

Cherubael1010 two things. 1. The item wagon issue is indeed the stack size on the station. This can be adjusted per station both requester and provider, or globally in the settings > per map settings. The fluid wagon is a bug only for trains running greater than 500K of fluid. This bug has been fixed in 1.0.11 and 2.0.11. Please update the mod.

It worked, the fluid wagon is now carrying at max capacity, thank you very much

Awesome! Start a new thread if any other bugs or feature requests come up. I'll lock this one for historical reading.