Correct me if I'm wrong, but I'm pretty sure it has always been that donation bots don't accept unusuals due to the constant shifting of prices. Of course, I very well could be incorrect, but I do recall that being the way it is somewhere and did not just make that up. :/ I personally don't have any unusuals so I can't test this for myself, but for those who do, please do check so that we can understand more fully why this happens.
~16