i have noticed sometimes videos load to 99% and can hear the audio on 4k streams but no video, i have to exit Netflix and load the 4k sports bar mode then enter Netflix again and everything works fine.
This issue was only for us with 1080i/p TVs, and it was trying to force the video to HDCP 2.2 which is for 4k... Though for me moving my TV to another output on my receiver that didn't support HDCP 2.2 fixed it for now.