I've tested this multiple times with all variations, such as the source_entity, is_projectile and is_explosion conditions (which work fine on their own), and it seems as though fireballs don't trigger this when the victim entity is a Blaze. I've tested the fireball trigger with other mobs and it seems to work completely fine. This code also works fine in version 1.18.2.
{
"criteria": {
"requirement": {
"trigger": "minecraft:player_hurt_entity",
"conditions": {
"damage": {
"type": {
"direct_entity": {
"type": "minecraft:fireball"
}
}
},
"entity": {
"type": "minecraft:blaze"
}
}
}
}
}
This is a case of MC-193297, since blazes are immune to fireballs as of 1.19, but are still damaged by the resulting explosion.