Note: I tried my best to search this issue and was unable to find one, I apologies if this is a duplicate.

Observers moved by pistons, activated by a 1 tick pulse don’t update Redstone properly. They seem to not power the redstone, under certain circumstances.

How to reproduce: Place a piston, with a Observer on its face, and connect the output of the observer to the piston. After updating the observer, or powering and de powering the Piston, it will creat a Redstone clock. Notice how the Redstone not visually powered but it’s still creates a clock. Any(as far as I can tell) Redstone components will be powered when connected to the Redstone powering this circuit, but will not when connected with a repeater or comparator. If you replace the observer with a redbone block, it will creat a Redstone clock with the exact same speed, but the Redstone is visually powered and will power other components. 

This bug happens in Creative and Survival game Modes.

This is a strange bug and is tricky to explain, I also attached some screen shots and videos demonstrating this bug. 

See attached screen shots for circuit that can be used to demonstrate this issue.