In both of the screenshots shown, a redstone torch is connected to it own attachment block. When first created, it functions as a very fast clock circuit (which is what I expect) but it quickly gets stuck in the off state.

How to reproduce:

1. Place an opaque block with a redstone torch attached to the side and redstone dust on top.
2. Place another opaque block above the redstone torch.
3. The circuit will "blink" several times before turning off.
4. Remove the upper block from the clock circuit. Place two redstone dust on one side to connect the torch to its attachment block.
5. Again, the torch will blink rapidly before turning off.

In both cases, I expected the circuit to remain in its "blinking" state, to create a very fast clock circuit. Instead, it turns off a couple seconds after. Placing/removing a block next to the torch (to create a block update) sometimes reactivates the circuit, but I get the same deactivation issue.

While this bug does not break redstone as badly as MCPE-15793, it makes certain redstone builds difficult.