Try factory reset of device (exclude and include it again). I had a lot of problems with Fibaro sensors in past (false alarm, battery drain, stuck on alarm state), replaced them with much cheaper Aqara and everything works as it supposed to. Other alternative Neo Collcam PIR, its zwave and also works without issues.
Then there is some other issue in your case. Aqara responds immediately. Im using it also for staircase backlight and it works in 100% of cases when I do enter the staircase. No delays, no false alarms, no dead sensors.