Some graphs for Oracle RAC do not show the complete list of the individual nodes' hostnames and gets truncated.
When the chart sees that there isn't enough space for the labels, it truncates some of them automatically. This is done by design so it won’t write one name over the other. You can still see the labels by hovering over it. Internet explorer seems to work slower so hovering won’t always show the data before the refresh (because of high refresh rate for this page). You can always freeze the time and then hovering on the chart works. Alternatively, Chrome works faster and hovering will always work with that.