When changing a painting's "motive" via a /data command, the texture remains the same until you leave and reenter a world.

To Reproduce:

1. Place a painting (Assume "kebab" for the sake of example)
2. Change it to an "aztec"

/data merge entity @e[type=painting,limit=1] {Motive:"minecraft:aztec"}

1. Note the console will tell you the NBT data has been updated, but it still displays as a "kebab".
   1. Neither a reload of chunks (F3+A) or textures (F3+T) will rectify the issue.
2. Leave and reenter your world, the painting will now display as an "aztec"