I have a Delightful Muse in my inventory and the transform doesn't work. When I click Transform Item it goes to the next step, showing the Delightfully Carefree Antler, but when I go back to inventory, I have the Muse, not the Antler. I'm using latest Firefox and tried in Opera, but no Antler.

You need to actually click to choose the Antler.

Oh my God, I'm sooooo~ blind!! Thank you!

It's a lot more obvious with items that have multiple transformation options, so don't feel bad. ^^