Generating Report Interfaces appears Gaps independently of Time Rage reports
How to fix the Gaps in Interfaces reports
Cause of Gaps:
The device or component does not respond to a poll request.
The device or component is down
A network problem causes the poll response to be lost.
The Data Collector/Aggregator is down.
Bad poll occurred.
Or a counter rollover because incorrect Vendor Certification Priorities
For counter rollover just change the Interface location in Vendor Certification Priorities
On Metric Families select Interface, edit Vendor Certification Priorities, moving Interface for Order 11 (after High Speed Interface) like as show on http://serviceassurance.ca.com/im/ Metric Families / 3.5.0 / Interface
Also check the Gaps Appear in Reports or Views on site: