In a setup where a shulker tries to shoot a player, but hits itself, it will sometimes teleport away and create a new shulker, but other times the shulker will not spawn.
In a setup where a shulker tries to shoot a player, but hits itself, it will sometimes teleport away and create a new shulker, but other times the shulker will not spawn.
I believe this is intended, Shulkers won't always spawn a new Shulker when hit with a Shulker Bullet, to quote the wiki:
"The chance of this happening decreases with the amount of shulkers in an 8-block radius; when more than 5 shulkers are present in the area, no shulkers will spawn. The probability is reduced for shulkers with less than half their health remaining."