Comparator Locking State when Chunks Unload

When I use a comparator on my SMP survival map and either log off or go into the nether it locks it's state and I need to break it and replace it for the comparator to work again. In a sorting system I have I have two comparators next to one hopper that then leads to a torch. If there are more than 22 items in that hopper the torch the comparators will produce a stronger out put turning off the torch and letting the specific item being sorted into its respective chest. The problem is when I log off or go into the nether or even go far away from my base the comparators will lock their state. For instance there could be 5 stacks of cooked chicken inside it and it will still only output a signal strength of one. This is clearly a bug that probably affects a lot of red stoners.

Thanks!