I step on an item, the same turn when the dungeon part I'm in is shifting. The only message I get is the "A whole section of the dungeon shifts to the west! Everything is shaking violently!" and nothing about -item- lying here. Then again, messages about monsters attacking me when the dungeon shifts are generated correctly.

The issue only seems to be when actually being in that part of the dungeon. When I'm only seeing the shift, not being on it, all seems fine. ("A whole section of the dungeon south of you shifts to the west! Gloves (6s) are lying here.")