Redstone signal through barrels breaks after reloading chunk

When a redstone signal is sent through a barrel, initially it works as intended. When the chunk gets unloaded however the barrel stays in a permanent redstone state and can't be updated. For example in the picture this simple mailbox design is meant to allow the player to turn the redstone torch on and off with the lever. It works when the barrel is first placed but when the chunk is reloaded the lever has no effect on the redstone torch.