Joomla: Profiles cannot updated anonymously

I have 2 public profiles on my site, one for editing a user's profile and one for opt-out.

The form directed the user to enter their email address, first and last name as they appeared in a token-generated email I sent them, then complete the profile with their address, communication prefs, etc. This form is a Joomla Civi>Profile>Edit menu link.

Before the upgrade to 3.1, Civi would realize it was a duplicate entry and quietly UPDATE the profile with the user supplied info. For my purposes, the first/last/email match with reCaptcha is good enough security. I did this all without messing with Joomla accounts since 100% of my database doesn't have an account in my Joomla instance.

Now, when public front end form is filled out, it only gives the error:

–
Please correct the following errors in the form fields below:

• A record already exists with the same information.
  –

Additionally, the reCaptcha module doesn't show up in this profile, even though it is enabled in the profile settings.

I have made sure that "Update profile on duplicate match" is checked in the profile settings. I have tried using the 7-day checksum token, which didn't seem to work with Joomla, so I abandoned that (perhaps a separate issue altogether.)