Confirmed for 1.13-pre1
Confirmed for 18w20b
Confirmed for 18w14a
Confirmed for 18w11a
Confirmed for 18w10a
Confirmed for 18w09a
Confirmed for 18w08b
Confirmed for 18w03b
Confirmed for 18w02a
Confirmed for 18w01a
Confirmed for 17w50a
Confirmed for 17w49b
Confirmed for 1.12.2 and 17w48a
This has significant consequences with the new "execute store" command variant since it appears that new values cannot be stored in the Pose data unless it is already different from the default values.
For example, the following command should update the rotation of the targeted armour stand's head (about the y-axis) to the value held in it's as_pose score:
/execute as @e[type=armor_stand,distance=..3,limit=1] store result entity @s Pose.Head[1] float 1 run scoreboard players get @s as_pose
but this only works if the armour stand's head pose differs from the default (and is hence stored in the NBT data).
Similarly, working the other way to copy the NBT data into the as_pose score:
/execute as @e[type=armor_stand,distance=..3,limit=1] store result score @s as_pose run data get entity @s Pose.LeftLeg[0] 1
will throw an error "Can't access element 0, either doesn't exist or parent isn't a list" and set the as_pose score to zero if the left leg is in the default position.
Window also gets wider
OS: Linux Mint 19.2 Cinnamon
Cinnamon Version: 4.2.4
Linux Kernel: 4.15.0-65-generic
Graphics Card: NVIDIA GeForce GT730