Nmap tracker not reliable

Nmap tracker, to track devices on my network, is not reliable.
i use the tracker to make sure my POE cams are working fine. if POE cams offline, send me an alert. nmap works great for about a day, then it marks all devices as offline…even though those devices are working fine.
here are my settings

is there a better alternative? seems pretty easy to do have something ping devices every few minutes.