Hopper timer possible bug

I started a superflat creative mode world with cheats on to test some redstone stuff. When i tried to make a hopper timer i put 20 Wool in one of the 2 hoppers and only 1 Wool started to go back and forth. The other 19 remained static in the one hopper. I clicked the 2nd hopper to take the item back whenever it was available every like 0.5 seconds from the one hopper to the other when I tried to click it the bug page of minecraft came in my screen and whenever I try to redo the same process the same thing happens