In Triib, you are able to pull a report of members who RSVP'd to a class, but did not show up and check-in.
You can run this report for a single day or over a timeframe. You can do this two ways:
1. Class List Dashboard: From the Class List Dashboard, click View No Show Report and it will pull the no shows for that day.
2. Reports > No Show: From your Triib Dashboard, navigate to Reports > Attendance > No Shows
From here, you'll be able to choose a Start and End date, and run a report showing all members who RSVP'd for a class and then didn't show up to the class in that time period.