Why can't I change the categories for my transactions?

On some of my transactions, they show up as "Garden & home" (or something like that) as the category. They are bank transfers, so I have no idea what that has to do with gardening. I cannot change the category, however. I click on the transaction and then click on the category button, but nothing happens. With all my other transactions, doing this same thing makes a box appear with a list of categories and I choose the correct one. Is something broken? Has anyone else experienced this problem? Why can't I change the category on some transactions?