Why doesn’t refine all work. I have torefine each one seperate
The current UI design intentionally separates different kinds of feedstock into different processing stacks.
Since it’s intentional, there’s no answer to “why” beyond “the developers wanted it to be that way”.
they are different. it takes 5 of the same herbs to make quality level 1 to level 2. then level 2 to 3. that is the difference.
Yeah I had like 300 one quality and I had to keep hitting refine cause refine all wouldn’t do anything
Bigger question to me would be: Why do you use refine herbs AT ALL. Its the second expansion this feature has been put in, and tis still as asinine as ever.
300xr1 herb? Lets go with the most basic herb? It takes 5Xr1 herb to make 1 R2 herb. Then 5Xr2 herbs to make a R3 herb. R1 mycobloom is 9g… R2 mycobloom is 9g… r3 mycobloom is 11g… The maths comes at a loss to me here. With mycobloom it goes from a stack of 300 R1s worth 2.7k… To 12 R3 worth 132g?
Even with the costy ones like luredrop and the spears. Why refine AT ALL?
Every once in awhile the math works out. Sometimes the R3s surge in price or the R2s crash. But yes most of the time it will not be worth it.
If you run 13 max level toons with all professions and I make almost everything for my own toons, instead of buying upgraded items, you upgrade them yourself and provide top quality items for your own toons.
This is the basic reason for the upgrading ability. 
Using the AH to upgrade your mats saves time and makes you money, but if you want to do it the hard way, more power to you.
BTW, “the hard way” includes putting up with bugged behavior no one will ever fix and doubtful design decisions no one will ever change.
If you have any small stacks (less than 5) that can be combined into larger stacks, do that. Seems that when you click “refine all”, it has a chance to try to pull from your stack that is less than 5 and then gives you the “requires 5 xyz” error. Also if you have a stack that is smaller, but still greater than 5, use that one first. Seems to avoid the error when following the two aforementioned rules.
Also, to explain why you’d want to refine them… some items result in much larger net profits at t3 than t2, making the increase in cost yield a larger return. Think t3 flasks going for 1k while t2 go for sub 200 a lot of the time lol.