No longer logging data

For some reason, Slimstat seems to have (almost) stopped logging. I’m seeing occasional entries appearing, but nowhere near the volume that I should be getting.

URL: https://essexham.co.uk

Server reports multiple instances of the following error:

[Thu Oct 09 10:20:59 2014] [error] [client 81.152.188.60] PHP Warning: Invalid argument supplied for foreach() in /var/www/vhosts/essexham.co.uk/httpdocs/wp-admin/includes/plugin.php on line 1515, referer: https://www.essexham.co.uk/wp-admin/admin.php?page=wp-slim-view-1

Tried clearing the cache and checking for MySQL errors, as per other suggestions.

Any thoughts?

Thanks,

Pete

https://www.ads-software.com/plugins/wp-slimstat/