Steps to reproduce:

1. select a graph where items aren't collecting trends, just history
2. click on last 2 days - graph shows data
3. change time period to now-3d to now  - click apply
4. graph no longer shows data.  

Result:
I've attached screen shots showing that if I pick same day last week or variations of that, the data is indeed in the history database

Expected:
reading documentation it is indicated that one should see graphs from history data if trends are not being collected.