/testforblocks giving some false negatives until relogging

Partner Rank: 2

Verification builds: Beta 1.12.0.3

Summary: In Adventures in Khundalan, the first quest is essentially broken because a /testforblocks comparison command gives a false negative until you relog.

Impact Clarification: It's possible this breaks other similar mechanics elsewhere in this or other maps, but none have been specifically identified at this time.

Repro Steps:

1. Download Adventures in Khundalan from the store and create the world.
2. Enter creative mode and fly over the sign showing the map logo.
3. Proceed forward past the branding logos and look left.
4. Right-click on the "Lamplighter" vindicator.
5. Right-click on the hopper to his right (below the redstone lamp).
6. Move one of the lamp fuels in your inventory into the empty slot.
7. Close and reopen the world.

Expected Results: The redstone lamp becomes a sea lantern immediately after adding the fuel, and relogging does nothing.

Observed Results: The lamp does not change until relogging, indicating that the distant /testforblocks command comparing the hopper with a template was wrongly failing. After relog it starts correctly succeeding.

Screenshots/Videos attached: Yes, video of me performing the repro steps: https://streamable.com/8d9ym

Notes:
The template hopper is located at 1984 70 1986.
The /testforblocks command block is located at 1984 73 1987.