[Register Plus Redux] Email Verification Not Working w/ DirectoryPress

In my Register Plus Redux plugin, I have checked off the option to have the users verify their email since I now have them entering their own password instead of sending one to their email address.

After registering, it says: “Registration complete. Please check your e-mail.” The message with the link is received but when I click on it, the link just takes me to the login page.

Nothing is verified however. I try to log in and get:
“ERROR: Invalid username. Lost your password?”

Meanwhile, the admin email is received, saying that I have a new user and gives me their unverified username (unverified_xxxxxx).

Any idea why this is happening and how to fix it?

I’m using Directory Press theme, which recommends Register Plus Redux.

Thanks for any help here.