Have you tried both the app and a browser? Try logging out and back in. It's possible that a restart of the camera using the button in Settings, My Devices, your camera may help.
I have the exact same problem. I never had the issue until I added a second system of the same type, but in a different location. A single camera at that location. This camera is CRITICAL to the safety of an elderly woman. I need resolution asap. I have a total of 5 cameras running combined with both systems. The second system with the one camera is the only one with the issue. I have rebooted everything, The camera says it is on, and there is no apparent errors in any settings. The camera has motion several times daily, and quick registering two days ago. THis is a serious problem!!!
I have even tried disabling the 4 cameras on the less critical system, and problem remains.
Same issue on phone app, and in window. The fact that there is no registered activity in the same time period tells me its not the interface.
Oh, all cameras were working as expected for several days.
I go to the My Devices, and was going to see what Camera potisioning would show. Well, both Camera Positioning, and Motion Detection Test show "(Busy)". I cant seem to do anything with it.
Ok, an hour after I posted my update... it started working again. First time in two days. I didnt do anything on my end. I really need to know if someone did something, because I need to be able to trust this thing. When I leave town, i have to have it working.