Not updating redstone signal

If I am making a button work like a lever using the following redstone build, redstone signal on the output doesn't update after the second press of a button - block remains powered even though it doesn't have any incoming signal, updating the block fixes the problem.
P.S. I couldn't attach the video because of it's size (I have attached screenshots instead), here's the link to youtube:
https://youtu.be/YXJXFEMcSJo