lennie76

I had to turn of a setting in the ShiftNav Plugin

“Shift the body of the site when the menu is revealed. For some themes, this may negatively affect the site content, so this can be disabled.”

Once disabled, the Lightbox began functioning as expected

Seems to be conflict with the menu tool I am using. Shiftnav

As an update, I commented out line 538 in the userlogin.php file and now everything is working as it did before.

The error cited above was still there however.