This is not a bug and its working fine
if your depots are full of your plasic , alloy , metals, its because you have not created a TRADE DEPOT http://simcity2013wiki.com/wiki/Trade_Depot
you need to build a Trade Depot and also have the correct storage addons for plastic , alloy and metal if you wish to recycle.
The Trade Depot not only allows you to make loads of money and export these materials to other citys BUT.. also it your own distribution network for your own city if you require these types of goods for use in your own city workds for coal, oil , ore etc... as well