I had a hopper loop with an item in it going in circles as a clock. The easiest way to stop the clock was to place a lever on top of one hopper and flip it. When I flipped the lever, it disappeared.
edit:
As stated in the comments below, it may be related to mc-59360 and affects also other non-solid blocks as stairs and slabs. But instead of popping out, levers just disappear.
Linked issues
duplicates 1
Comments 3
No, it didn't fall into the hopper. I tested it on a single hopper not attached to anything. Tried in creative and in survival. I flip the lever, hear the sound as it flips and it just disappears. The hopper remains empty.
edit
Yes, I tested it, it may be related. Happens also with stairs and slabs. But instead of popping out, the lever disappears.
The lever item dropped into the hopper, and this glitch is likely related to MC-59360.