I attached a zip file of the world: the affected piston mechanism can be viewed at coordinates -232 6 112, and can be tested by placing and activating a lever at -233 6 113. Placing a block (or giving any block update) right underneath the piston, in block -232 5 109, while the top piston is activated and the bottom isn't but should be will activate the piston. I implemented a temporary fix on the other side of the redstone contraption, at -240 4 111, that gives a block update to the piston 5 redstone ticks (10 game ticks) after it should have extended.
I have had this and I am pretty sure it is an MacOS bug rather than a Minecraft bug, if you leave the window, click on blank space on your desktop, go back into minecraft, and click, it should go away.
It is possibly that bug, but it does not make sense that it would be considering that this bug did not happen before 1.20.