Steps to reproduce:
- Start a single-player creative world.
- Place a cobweb above a funnel with 1 block gap.
- Drop an item into the cobweb.
- The item will vanish into the funnel's inventory without ever falling out of the cobweb.
This appears to be a case of the hopper claiming any item in the space 1 block above itself, rather than waiting for the item to actually touch the hopper.
Items dropping in at normal falling rates seem to drop in reasonably — I suspect that in that case, the problem is masked either by a time delay or by server/client desync (which seems to be a problem for items lately; I keep seeing them jumping around, ever since the update which changed items-popping-out-of-blocks behavior).