Steps to reproduce:
1. Type in a command block any teleport command: /tp ~ ~ ~
2. Summon a fireball anywhere by using this command: {{/summon Fireball ~ ~ ~

}}
3. Use a bow or a snowball and shoot into the fireball in whatever direction
4. Notice that the fireball only flies in one direction
What should it be: Fly accordingly of the direction of the snowball/arrow
P/S: Punching the fireball by hand while running the /tp command is still fine