Any vertical hopper chain refuses to gravity bleed downward correctly (expected result not happening). Using 5 vertical hoppers in this example. Building it in the nether if that matters. Sometimes refuses to pass items through top most hopper (no gravity feed at all), sometimes passes a few items through then locks, sometimes passes all items but 2nd or 3rd hopper down refuses to pass items. No redstone nearby and no trapped chest (regular chest on top of hopper chain). Vertical hopper mechanics acting erratically.

I haven't done any more testing with hoppers only a vertical hopper chain because that's obviously enough for me to report the bug as it is. Recommend more testing on your end with hoppers.