I looked at the code
The Portal room has
- Use Item - Default Command
- Activate Portal - Can be seen after the quest to open the portal with Illiana is complete
- Use Portal - Can seen once portal is active and you have some related task (like get Nyx)
This works 100%. Check you quest log for what you might still have to do. Maybe talk to the queen and activate the portal.
Please also note that the game does not work with mods and especially not with URM. If you use that there is nothing I can do. It will corrupt the game data and all kind of weird things happen (like UI buttons missing...)