So…when attempting to add a user to a site from the WP Admin -> Users -> Add New, I got the “You must drag the proper image to the circle” error, which if I am not mistaken, is generated by the SimplePress login/registration option.
I was able to work around this by disabling “Use spam tool on registration form” from the SP Components Admin. It just seemed odd that the error message should appear in the backend, when the actual spam tool did not.
FYI only…
Was this you adding the user logged in as a Forum Admin user? And do you have the captcha plugin turned on for your users as a matter of course?
that would indicate that the wp admin area was using the same hooks as the front end registration page which would be quite foolish (at least at first blush)… and certainly not something we have seen in standard wp…
a quick check of wp core and I dont see any usage of similar filters in multisite either…
Are you running any user, registration or membership type plugins?