Just lately i have noticed that when i use AF-C with my Nikon D750 and the Nikon 70-200 vrii 2.8 that the focusing on the lens keeps trying to focus on the subject, it use to lock on straight away, but now i can hear the motor focusing in and out really quickly. Put the camera into AF-S and its fine. Put the 24-70 lens on, and select AF-C theres no issue.
Time to send it into Nikon I guess.