I am a strong believer in having items categorized in your eBay store. Today I spent the day redoing my store’s categories via Manage Store Categories.
Due to a long existing ‘bug’ in the eBay Store Categories system things like moving listings from one category to another via a delete category, OR moving category within/out of each other is known to ‘take a while’; in short if you try doing too many moves too quickly you will get an error that says:
You cannot move categories until we've completed your previous request.
If you do, try again, it should work again after a few (5~15) minutes.