Steps to reproduce:

1. Create new item history widget on a dashboard
2. Choose more than 1 host with same item for columns
3. Save the dashboard and test by switching the filter time periods
4. For up to 2 days the data is consistent, but 7 and 30 days on occasion had issues and on 3 months it only shows 1 host history entries (hourly trends)

Result:
Only 1 host is shown on 3 months and longer periods (perhaps due to timestamp being identical from hourly trends?)
Expected:
Even when using trends, all hosts data points should be populated.

Attached there are the images explaining the behaviour as well.

Images show filters starting from 2 days up to 1 year. Issues start appearing on 30 days filter as the returned data is not most recent any more.
On 3 months filter the data returned is 3 months old and also z.test... item is only shown 3 times in the results.
On 6 months and 1 year filter the data returned is older accordingly and z.test... is no longer visible at all.

Also included images of the history graph for both items with 1 year view showing that both items do have 1 year of history.