Order icons doens't work for custom icons

+1 I was just going to post the same comment but you beat me to it.

Just to point out, you can order your custom icons by adding all your URLs, saving, and then selecting one of the predefined icons. This will allow you to drag and drop reorder them, save, and then switch back to custom icons. You won’t notice a change in the widgets page, but it successfully holds on to your custom order.