I used the WP Rollback plugin to rollback Phlox Portfolio from version 2.3.7 to the older version 2.3.5 and disabled updates. I then uninstalled and reinstalled the Phlox Core Elements plugin, by doing so the text parts of the site started working. Unfortunately the plugin cannot be undone, the portfolio stopped working altogether.
I don’t know what to do next to get the portfolio working again.
The plugin has been temporarily closed on the WP site.