I have the same issue, I had tried so many configurations that am tired of it, tried many camera's as well, 1.3m, 2m, 3m and 4m Cams! I only have one good camera in C4 GUI, not able to ever duplicate it to any other camera?!!
Had Contacted C4 and gave them access to my system, never came back to me or responded with a solution! I also opened 2 tickets for IOS bug, again, nothing back, reminds me with HouseLogix ...
Anyways, I will remove Amcrest driver and use BlueIris as I do have tons of issue with NVR/DVR driver, it always gives Invalid and have to reactivate it every week! I'm also running Cams outside of C4, at least its working great.