1.2.64b Clearing data history doesn't affect usage statistics and graphs fast enough

This problem has existed for several versions because many times I’ve tried to clear my history using Settings > Clear History: All > Clear and found that the Usage statistics don’t change.
The Graph view shows that the data is cleared:

But the Usage view does not:

If you see my earlier post you’ll see when my usage past 1GB

The issue is a bit more complicated because the Graph views are also scaling incorrectly. I suppose that they may be using the usage data for scaling but only displaying the data after deletion or some strange combination of the same:
3 Hours 3MB
24 Hours 10MB
Week 200MB
Month 2GB
Years 2GB

The usage stats and graphs are displaying correctly now but it took 15 minutes which is way too long!

Investigating, thanks!