Data is not lost, just a bug in the chart report.
Go to Plugins > Editor and choose WP SlimStat from the dropdown in the top right hand corner of that screen. One of the first lines should be
Version: 3.5.7
Change that to 3.5.6 and save. Then head to the Plugins screen again and wait for WordPress to warn you that a new version is available. Upgrade and… voilà, your data will be back 🙂
A review for SlimStat would be a nice way to say thank you
http://wordpress.org/support/view/plugin-reviews/wp-slimstat
Thanks camu
I had the same problem as “Pipa Hoeta” and tried to do as you says in your post above.
Worked just fine
Thanks
Thanks!
By the way, I have already reviewed SlimStat (with 5 stars) : )
Version 3.5.8 should solve the issue for good.