Steps to reproduce:

1. Create an item which collects numeric data with
   1. Interval: 1m
   2. History: 1h
2. Go to latest data and verify that some data has been collected.
3. Create an ad-hoc graph for that item and choose 1h as time span.

Result:

As you can see in the screenshot Zabbix claims to have no data:

I you choose a different time span (here 30m) the data is correctly displayed in the graph:

If you increase the item's history period to 7d the the 1h graphs is also shown correctly.

The behavior also happens with graphs which have been created for the host/template or within a LLD. If a graph shows multiple items the issue only occurs with the item having a 1h history period. The other items are not affected.