For some ungodly reason I'm unable to change my shaman colour.

It's currently set to "A90101" and has been like that since shaman colours have been change-able.

I'm unable to set it to anything else.
I've tried pasting codes in and clicking "Submit"
I've tried to pick the colour myself without pasting in a code.

It just refuses to let me set any other colour apart from "A90101"

When you change it don't open it back after because it'll be the same shaman color which you had before.

Do you have an outfit with that shaman colour saved?