Default alchemical mixing recipes display all 5 default aspects, even if they are not used. Additionally, if these recipes are removed successfully, they still show up in JEI.

Following a conversation with Daedalus, I have discovered that you must remove Alchemical Mixing recipes with the right stack size.
Don't - mods.soot.AlchemicalMixer.remove(liquid:antimony);
Do - mods.soot.AlchemicalMixer.remove(liquid:antimony*12);
"it checks it against the output of the recipe and it will only match with equal stack sizes"

In case it is not clear, I am talking about removing Alchemical Mixing Recipes using Crafttweaker. Leaving this here in case anyone else experiences the same issue.