Thanks for replying!
Yes we still receive other email, and “Post Update” messages from Sucuri. I changed the keys for both sites, that did not seem to solve the issue.
I do not see a SUCURI_DATA_STORAGE variable on that page. In Settings -> General the “Data Storage Path” is the following:
/home/$SITE_NAME/public_html/wp-content/uploads/sucuri
This seems reasonable and does not conflict with the test site on the same server. The files seem to exist and be writable according to that page. I am going to try turning on debugging at the WordPress level and repeat the error in order to see if I get more information.
Regards,
