We have one location that has capacities that vary. The location capacity is a certain number, but the events we schedule may have less capacity, depending on the time of the year. However, the Location Availability shows that there are more spots available in that location, even if the event capacity itself or the Event Attendance report does not show that many available.
The Event Attendance Report is looking at the capacity of the event remaining (Tickets > Program Search > open your program, Event list tab, look at Availability), but the Location Availability is looking at the capacity of the location remaining (Tickets > Locations > look at the capacity column next to the location of the event).
If the capacity of your location differs from the capacity of your event, these values will not match.
For example, you may have a location that can be used for several events at once and has an overall capacity of 100. If you have an event that only has a capacity of 20 that is using that location space, the Event Attendance Report will show Available 20, but the Location Availability Report will show Available 100.
Steps to Duplicate
Go to Events and select the Event Attendance report
Set the Event type to All, Group by to Event, and Date to the specific range
View the report and see the values for the Available and Sold columns for a specific event.
Go to Sales and select the Location Availability report
Mark the box for only the location for your event, set the Availability to Unavailable, and the date to the same range as the Event Attendance report.
View the report and note that the values for Available do not match the Available values in the Event Attendance report