Motion NBT tag in execute selectors doesn't seem to be checking actual values

When using a command with the motion NBT tag, such as @a[nbt={Motion:[0d,0d,0d]}], a command block does not appear to check player's motion.

Using a single player world, I have a repeating command block set to always active with the command: execute if entity @a[nbt={Motion:[0d,0d,0d]}] I then attached a comparator next to it to see when it is successful or not. When I am not moving, the comparator is active as expected indicating it found a player with a motion of 0 (me). However, when I start moving so that I have a motion unequal to 0, the comparator never turns off as expected since it should not be finding a player with a motion of 0.