The first time you hit a page after the upgrade you’ll find a delay as WP Satistics processes the database changes, if you wait a bit the page should render when that completes. Otherwise, reloading the page should also work fine.
I had the same problem…. repeated refreshes, no errors in PHP logs, admin page was blank (2 – 3 mins wait, followed by refreshes) and post-content screens stopped content display at point the widget was executed.
I manually disable the plugin by renaming the directory to verify the issue, then restored the name … and the problem seems to have gone away. The widget runs as expected, the admin panel is back and all seems well.
On a second look, the errors I have in my log are not from this plugin, they just happened around the same time. Sorry about that.
However, I have still not found a resolution. I tried renaming the directory and then installing the plugin fresh, but that did not work.
I checked a 3rd site I run that uses this plugin, which I have not updated yet, and it is running 6.1. I usually updated all my sites around the same time, so on the two sites I am having an issue with, would most likely have gone from version 6.1 to 7.0.1