Put the summary of the bug you're having here

What I expected to happen was that if I placed a block where the dropped items were, they would move into an adjacent air block.

What actually happened was that the items disappeared and even after mining out the block I placed to move them they were missing.

Steps to Reproduce:
1. On a flat plane, dig out a 1x1x1 hole
2. drop any item in
3. place a solid block, like cobblestone, in the 1x1x1 hole. The items will despawn