If the homestead is under attack, that needs to be ended before any more portal will open.

Where is Zixzax? If he is beside a portal or the statue, then you need to enter the portal, get a cutscene conversation with Astarte or the demon, then return to the main section of the homestead through the portal in order to finish opening it, and have Zixzax continue.
A marker is placed on the map when a portal has been completely opened, so check for an activated portal with no map marker.

If you don't see Zixzax, check the paths left and right from the entrance, keeping any eye on the mini-map for green dots. After the first elemental portal is the Hall of Secrets (left), another elemental portal and then the Hall of Darkness (right).

Check if you can speak to the statue, to select an elemental portal.