You may see this for example, when the view is set to a resolution of 1-Minute and:
1) You are reporting on a device that has interfaces with a mix of 1-Minute and 5-Minute polling and are reporting on an Interface Metric at the Device level.
2) You are reporting on a time period with a mix of 1-Minute and 5-Minute polling, for example, if you recently enabled 1-Minute polling and are reporting beyond when it was enabled