I don't have an Airsight so I can't help much with you issue.
It does sound like a bug in the software.
However you'll still get multi pics of nothing even if it worked on schedule as it looks at pixel changes from one shot to the next.
You may wish to look at using a x10 motion sensor & PC interface with some software to trip snapshots.
This will also result in some false trips but not as many
I'm currently adding more IP cam support to
PCC Although it won't be as in depth as Blue Iris I'm hoping to have some of the basics.