I died of fall damage on a tree. When I went to collect my items, I was able to collect all except 3 of them. They fell to the ground after I broke the leaves I was on. I couldn't pick them up. They then kept teleporting to where the block they were on was. They then despawned.

What I expected to happen was for the items to be picked up.

What actually happened was: My items could not be collected and thus disappeared.