Why did I hear “ka, ka” noise in the process of reading 4K Ultra HD(UHD) Blu-ray Discs? And the reading process was failed at the same time.

That noise meant that the ASUS BW-16D1HT had gone into “Sleep” status.
You need to reject and reload the 4K Ultra HD(UHD) Blu-ray Disc to wake it up. And restart the reading process

Updated : Apr 18, 2019.