Blue Iris

On a partly cloudy day the clouds sliding by create ground shadows and it causes the cameras to trigger. I have tried everything I can think of but nothing has worked. It is not uncommon for me to return home to find that there are hundreds of cloud triggers.

Have you tried 'Cancel Shadows'? This may reduce triggers, but it will not eliminate them.

I use 'Zone Triggering' on a few cameras, which has reduced triggers caused by clouds to almost none.

The only way I've been able to eliminate shadow triggers and still get reliable motion alerting for people is using AI person detection. I have tried Sentry AI which is a simple check box in each cameras properties but requires a subscription to their AI service for something like $60 a year. I've also tried the free DeepStack and AI Tools combo which is completely free but a bit more work to setup and on a reboot requires a few seconds of manual intervention to get it up and running correctly each time since the DeepStack component isn't designed to run as a service on Windows for some reason. Both methods work equally well once they are up and running at eliminating false alerts down to about 98% reliability in my experience.