After system restart 14 of 62 cameras have no video but each camera’s web ui has video.
Not knowing what kind of installation you have or what XProtect version, neither a camera model, it is a but hard to give advice.
What you could try: Run a hardware replacement and see if you can get the missing cameras back. Try on a single cam first. If it fails, pls contact Milestone Technical Support (through your Milestone partner).