I recently upgraded to the brand new ELK version 7.5, everything is working great except one annoying issue at the Discover's Pane:
I have an Index which contains 2 years worth of data, each document is timestamped (using the Date field), but documents before a specific date have missing/null values in one of the fields (which is not the Date field).
Whenever i set the Date's range to show data with documents that have null-value in the specific field, the Date histogram (at the top of the Discover's Pane) suddenly disappears.
In other words, the Date histogram is showing only when i filter the index to show only documents with existing value at the specific field.
I couldn't find any setting to solve this in the documentation.
Before the upgrade i was using ELK version 6.5 and i had no problem of this kind.