I have built the same redstone machine in two different worlds in SP and only one works. Both are creative superflat worlds with cheats on. I tried to reset all gamerules in the non-working one to the defaults as I did not change them in the working world. I downloaded NBTExplorer and went through the level.dat to make them the same and nothing. When I go into the data folder the world that doesn't work has an a capabilities tag while the working one does not. I do not know what this means or if it makes a difference and the one that doesn't work has a serverconfig in the main world folder and the one that works does not.

Update: The redstone machine also works on a vanilla 1.15.2 server