I had a command creation that worked in 1.8 involving /summon Fireball ~ ~ ~ {ExplosionPower:3,direction:[]} which worked just fine. When 1.9.2 came out, it stopped working. I tried using the /summon command for a laundry list of entity
IDs, and all of them worked except for /summon Fireball, /summon SmallFireball, and /summon PrimedTnt.
For the fireballs, see MC-86011.
For the PrimedTnt, they summon fine for me.