Comparators measuring a non-empty container momentarily stop emitting power upon reloading

When i put a Chest then an item also theres a comparator connected to it then the comp is connected to a block with a torch so it turns off the torch when i remove the items however when i re-join the comparator resets it runs out of power for a few ticks (short)

Try to Build the contraption on the picture quit and re join you"re world the tnt will explode the chest on the item has a 64 diamond so it gives a signal btw
Samsung Galaxy S4 mini