UI does not show stats for minute granularity if clocks on node are not in sync

UI on Couchbase Server does not show stats for minute granularity if clocks on node are not in sync.

Steps to reproduce :

1. Create a 3 node Couchbase Cluster with ~2 minutes difference in the clocks.
2. Create a sample bucket and make sure there are operations on the Cluster for atleast 5 minutes.
3. Navigate to Ops per second graph for one of the buckets in the web UI.
4. Notice that the graph shows blank (See attached image).