we are currently using Piwik 1.8.4 for a client with different websites.
On the dashboard for one particular website in the widgets is only shown “There is no data for this report.” when you choose October as Date Range. If you choose “Date range: From 2012-10-01 to 2012-11-01” the data is shown. For other months choosen in Date Range the data ist also shown.
For example, I get the following results for my homepage when entering these date ranges:
2nd Jan 2013 - 1st March 2013 = 31,685 pageviews
2nd Jan 2013 - 2nd March 2013 = 17,873 pageviews
So just by shifting the date range by one day my stats are dramatically reduced.
I get this with numerous date ranges:
1st Jan 2013 - 1st March 2013 = 524 pageviews (so it appears there’s something wrong with 1st Jan 2013).
I’ve noticed this across several date ranges. Often just by changing one of the dates the stats are wrecked. This is obvisouly rendering all of my analytics kind of pointless at the moment.