Bug w/ vertibird in Synth Retention quest

Possible gamebreaking bug on PS4. In quest Synth Retention the synth keeps shooting at a spinning nearly crashing Brotherhood Vertibird. But it is indestructible. Can't talk to the Synth to progress quest. Any tips? Don't have saves from before the bug. Already slept multiple days and dis some other quests. HALP//

VID: https://goo.gl/photos/sJ5nd9FWbgKPUDRCA