This bug is closely related to MC-11193. However, the behavior depending on the parity of the redstone power signal is new in release 1.14; so I decided to open a new bug.

Pistons do not retract the majority of times if the redstone power from a solid block above was even, depending on their position

Look at the printscreen. If you press the right button, all pistons extend and retract, as expected. But if you press the left button, all pistons extend, but the majority of the pistons do not retract, leaving a state as shown in the printscreen, some extended, some retracted; not as expected.

If you rebuild the cirquit, you may get a different pattern, depending on the position. If you rebuild the circuit 16 positions right or left, you will get (in the cases I tried) the same pattern.

Furthermore, it turns out that:

• Prior to release 1.14, also pistons with an even power (right button), did not retract correctly.
• If you rearrange the pistons extending downwards, no piston with an even power will retract.
• If you rearrange the pistons so that their extended head is positioned under a powered redstone dust, all pistons will retract correctly.
• If you line up several pistons with no space between, they will retract correctly.
• If a piston gets an odd power signal (the right button), it will (since release 1.14) retract correctly.
• If you replace the solid blocks below the redstone dust with top slabs, everything works as expected.

Information about the cirquit/printscreen:
World Type: Superflat, Redstone Ready
seed: -3202485876541754533
Facing: south
Coordinates of leftmost piston: 9 56 11