I had an earlier version installed and working fine but recently decided to upgrade to the latest version. The modal appears as expected when I click "Create an Account" on my site but when I click "Sign In" the modal doesn't appear and instead it clicks through to my theme's standard html sign in page.
Interestingly if I click "Sign In", then click "Create an Account" both the "Create an Account" and "Sign In" modals appear.
I don't have time to troubleshoot at the moment for but thought I'd post in case someone already knows the answer. See my site here: