Steps to reproduce:

1. Enable Administration -> Housekeeping -> Override item trend period
2. Add item with trend storage off
3. Add some data for this item that spans 1 week period
4. Check simple graph in week period

Result:
See the attached video
Expected:
The graph must display data

As it's evident from the video, when I select <=2 day period the graph selects from history and shows the data. For periods >= week the graph mistakenly selects from trends.