One 'lazy' IP camera on NVR5216-4KS2?

BarkityBark

Young grasshopper
I have 6 cameras hooked up to my NVR5216-4KS2. One of them is always 'lazy' to display its live video in the split-screen or single camera display mode. The green outline depicting an active camera will be there (along with the RJ-45 icon), but the live video won't. Black box. After several seconds the video pops in, else manipulating the display from say, showing a 16 camera grid to an 8 camera grid, gets it to finally pop in and show on my HDMI monitor. Anyone have any experience with something like this? NVR software issue or camera issue? Poor connection/wiring issue?

FYI, I've ordered 3 more cameras from Andy, so I'll be able to swap the one causing the fuss soon, just to see if it is the camera itself.
 
Is the problem camera the same model as the others that behave OK?
Does the problem camera have different firmware from the others that behave OK?
Does the problem camera have different a configuration around the video and image settings?
And if so, what?