Here is the full statement from Dragonest:
There is unfortunate information that we have to share with you. We have decided to slightly delay the PlayStation 4 version release date of October 30. The new launch date will be informed immediately when determined.
We understand this is frustrating, but please accept our sincerest apologies.
Our purpose is to realize the cross-play on all promised platforms including mobile, PC, and console. Despite all efforts to sharpen the game in the past few months, the quality of the current PlayStation 4 version still does not achieve our expectations. Some extra time is needed to ensure that the game has a consistently stable performance, therefore we have to make this difficult decision.
We are certainly sure that the necessary improvements are worth waiting for. Now, we are having a lot of pressure, but we believe it will motivate us positively and significantly.