Are you still having this problem?

Your issue isn't the same issue as what the OP has! There is currently no achievement for Cacophonia Carapace, and it will be added later on.

I've just tried resetting your avatar, and can you please see if you can make changes now?

You will be forced to use the kumos wardrobe at some point in the near future.

For other folks - can you tell me how its' not working. Are you saving and not seeing an updated image, are you seeing an error when you save, are you not able to put specific items on? Please be as specific as possible.