This may because my client has a pretty old site (with tons of customization and a tight budget, ergo the reason we're not working with 3+ here) - maybe this is a v.2.9 issue, and not a WP Security Scan issue, but I thought I'd report it in the event this information is useful.
I recently updated WP Security Scan from v.2.7.2 to v.3.0.1, because the older version was throwing a server error. After updating, as described in some other posts here (see below), I couldn't initiate any of the jQuery functionality in the WP backend, i.e. opening items with the down arrow, dragging and dropping, opening the screen options, etc.
Checking Firebug, I caught this error:
$wsd_new_user_form.delegate is not a function
For now I've disabled the plugin (and all functionality was immediately restored), but if I can get a fix for this, or maybe a better idea of a possible conflict on my end, that would be great.
Possible related issues: