When updating the Motive tag of a painting, the painting doesn't update until you reload the world.

The behaviour's a bit different in different cases.

1. If you update the painting to one that's the same size, it will stay the same until world reload.
2. If you update the painting to one that's a different size, it will go invisible until world reload.

Expected Behaviour:

Painting updates when command is run.

Actual Behaviour:

Painting updates after command is run AND the world is reloaded

Steps to reproduce:

1. Create a fairly large wall
2. Put down one of the larger painting
3. Run `data merge entity @e[type=painting,limit=1] {Motive:"minecraft:aztec"}`
4. Notice the painting disappears. Reload the world, the painting will now be 'aztec'