That's because they are rollup fields (MSDN ref), which are handled by the system itself.
Rollup attributes
Because rollup attributes persist in the database, they can be used for filtering or sorting just like regular attributes. Any kind of process or plug-in will use the most recently calculated value of the attribute. Rollup attribute values are calculated asynchronously by scheduled system jobs. Administrators set when a job is run or pause the job. By default, each attribute is updated hourly.
When a rollup attribute is created or updated a Mass Calculated Rollup Fields job is scheduled to run in 12 hours. The 12-hour delay is intended to perform this resource intensive operation during a time that will affect users the least. After the job completes, the next time it is scheduled to run will be 10 years in the future. If there is a problem with the calculation, this will be reported with the system job.
Locate the system job in Settings > System Jobs to find any errors with rollup fields.