Last bit of news about this is that it may have been the police department's own drone spotted the first time that started all this.
You are correct...
The police have finally admitted that it was possibly their own surveillance drones that caused days of chaos. There may have been a single civilian drone that initiated the panic - or that could just be a cover story to divert attention from the actual embarrassing events. Hopefully the media will expose the truth because the authorities don't want to take the blame for all those cancelled flights.
Dec 29 update here
Footnote: Police even dismissed 2 drones found near the airport property as "not involved" which raises a whole lot more questions.