I also noticed that when a player is in a boat, a command block can not teleport the boat.
Command: /execute @e[ry=22,rym=-22,type=Player,tag=InBoat] ~ ~ ~ /tp @e[type=boat,c=1] ~ ~ ~1
Output: Teleported Boat to -1023.5002065873173, 56.0, 196.80990742076614
While the output says it teleported the boat, the boat did not move, nor did the player.
Changing the motion entity data tag does also not move the boat while the player is in the boat.
This is not fixed in the 17w06a snapshot.
Ender Invader
I also noticed that when a player is in a boat, a command block can not teleport the boat.
Command: /execute @e[ry=22,rym=-22,type=Player,tag=InBoat] ~ ~ ~ /tp @e[type=boat,c=1] ~ ~ ~1
Output: Teleported Boat to -1023.5002065873173, 56.0, 196.80990742076614
While the output says it teleported the boat, the boat did not move, nor did the player.
Changing the motion entity data tag does also not move the boat while the player is in the boat.