Sally2000 "I can monitor, control, and playback video from our Hikvision cameras using their own apps on Windows, Android and Apple.
What is missing?"
I had no problems with Windows, Apple or an Android phone until a couple of weeks ago so you may well find things changing soon. I've had a look at the Hikvision cameras on Amazon but couldn't find info about how they operate going forward in relation to the end of Flash. I keep Windows 10 fully updated. Are you running W10 fully updated too?
MisterG81 Reolink seems worth following up but none of the reviews I've read mention Flash - the elephant in the room.