Dungeons & Dragons is a love story, but Cryptic and Dragons apparently not. With Storm Kings Thunder an old issue reoccurred that disables all dragon type enemies. The Scourge Warlock powers Arms of Hadar and Gates of Hell seem to be affected. It’s a bug the Cryptic engine is prone to and the devs can’t seem to generally fix the issue.
Dragons can’t recover from CC
The cause is rather simply. Dragons can’t recover from CC because they shouldn’t have been disabled in the first place because of their immunity. So in case a power does inadvertently pierce that immunity, dragons are screwed. DCs have been able to stun them with Sun Burst and more recently the Paranoid Delusion companion.
This once again makes the Dragonflight event a pretty boring affair and only a matter of DPS. But not only dragons are affected, because the powers ignore immunities from other bosses and players as well. But those can at least properly recover from it.