[Sub-Mod] Dragonhunt - need some help with an anti-Targ CB

Looking for help modding for an upcoming series. I'm making a mod inspired by DubiousScrivener's fanfic Summer Crowns on alternatehistory.com. Basically, Rhaegar escapes death and flees to Volantis, and Robert Baratheon gives up his crown to Stannis to chase Rhaegar down. To fight Volantis he carves out a realm for himself as a mercenary captain for his all-star band, the Dragonhunt.

I want to give Robert a CB on anyone who harbours Targaryens. If he wins his war, he imprisons all Targaryens in his target's realm.

Here's what I have so far:

# Anti-Targ CB

anti_targaryen_war = {
name = CB_NAME_ANTITARGARYEN
war_name = WAR_NAME_ANTITARGARYEN
sprite = 7
truce_days = 1825
can_ask_to_join_war = yes
allowed_to_target_tributaries = no
hostages_block_cb = no
att_ticking_war_score_multiplier = 5.0
def_ticking_war_score_multiplier = 5.0
defender_unoccupied_warscore = yes
max_attacker_battle_score = 100

infamy_modifier = 0

can_use = {
ROOT = { NOT = { trait = nightswatch } }
ROOT = {
has_landed_title = k_dragonhunt
}
FROM = {
any_realm_character = {
dynasty = 496 #Targaryen
is_alive = yes
}
}
}

on_success = {
hidden_tooltip = {
ROOT = { add_character_modifier = { name = victory_timer duration = 3 } }
mega_war_rebel_leader_resolution_effect = yes
}
FROM = {
transfer_scaled_wealth = {
to = ROOT
value = 2
}
any_realm_character = {
if = {
limit = {
dynasty = 496
is_alive = yes
}
imprison = ROOT
}
}
}
on_fail = {
any_attacker = {
participation_scaled_prestige = -50
}
any_defender = {
participation_scaled_prestige = 50
}
}

on_reverse_demand = {
hidden_tooltip = { FROM = { add_character_modifier = { name = victory_timer duration = 3 } } }
any_attacker = {
participation_scaled_prestige = -100
}
any_defender = {
participation_scaled_prestige = 100
}
ROOT = {
if = {
limit = { is_liege_or_above = FROM }
imprison = FROM
clr_character_flag = captured_in_battle
}
transfer_scaled_wealth = {
to = FROM
value = 4
}
}
hidden_tooltip = {
mega_war_emperor_rebels_resolution_effect = yes
}
}

attacker_ai_victory_worth = {
factor = -1 # always accept
}

attacker_ai_defeat_worth = {
factor = 75
}

defender_ai_victory_worth = {
factor = -1 # always accept
}

defender_ai_defeat_worth = {
factor = 75
}
}
But the CB doesn't show up for Robert at all. I've tried moving Rhaegar around to different courts but no luck. Any idea where it's going wrong?