I don't think it is cancelled. The flight is delayed with a new departure time of 9:30pm and the inbound aircraft B-HPD landed slightly late in Manila.
Looking at the list of cancelled and delayed flights between Hong Kong and Manila and I presume it is somewhat weather related in Manila.

It is 10:20pm local time now, and PR 306, which is scheduled for a 4:45pm departure to Hong Kong, has just taxied to runway for takeoff.
CX 918 is possibly affected by weather too, either enroute or weather at Manila. Hong Kong had some heavy run this afternoon/evening so things just cleared out a bit in the past hour. Weather is possibly the reason for delays.

I checked expertflyer and other than showing the delay, they did not have any explanation of the delay.

Carfield