[Blocking xmas] /replaceitem on cmd blocks doesn't appear to work on mobile

Verification builds: 1.2.6 (578130)

Summary: Seeing some inconsistency between Windows 10 and iOS when executing the `/replaceitem` command from a Command Block. Works great on W10, but testing our Xmas content on iOS fails unexpectedly.

Impact: `/replaceitem` does not place an item in Chests and Furnaces on iOS.

Repro Steps:

• Add a command block and a chest
• Set the command block to place an item in the chest
• Run it
• Try placing the chest outside the same chunk as the command block if unexpected results

Observed Results:

On mobile, the item does not appear within the Chest or Furnace.

Expected Results:

The item should appear in the Chest or Furnace (as seen Windows 10 edition).

Screenshots/Videos attached: No

Notes: