The math is working just fine here, and nobody else has reported anything similar happening. Computers usually don’t make math errors, and this plugin has been around long enough that if I had made a mistake in the code that calculated the # of open spots, many users would have told me by now. But, it’s working just fine on my test sites and nobody else has reported anything remotely similar.
Sounds like either some data corruption in your table for the tasks, or user error.
If it’s a recurring event and you set it up for 3 different dates, then the total would be 45 (3 days, all with the same tasks of 15 each, makes 45). If it’s not recurring, then double check your tasks to make sure there was not a typo, and if not, then check the tasks table in your database to see if the numbers are wrong in there, or somehow some other tasks got assigned to the same sheet ID.
