Cannot create Ontology in the official Ontology Tutorial

Another update. Microsoft team discovered that the issue with not loading Lakehouse tables and columns was related to the Lakehouse API being inaccessible to the Ontology item. They are rolling up the update to fix that and it already started working in North American regions including Canada, but North Europe regions are a little behind.

Testing after the fix, I confirm that the official Ontology tutorial now works (tested in Canada and East US regions) but it only supports Lakehouse without a schema as a data source. An Ontology can be created from a Lakehouse with the schema enabled and data binding will work but the Graph instance that powers the Ontology preview will not work at all. So, for now, stick with the Lakehouse without a schema when using Ontology. It does look like a limitation, but there could be possible workarounds like Lakehouse table shortcuts, for example, which need to be tested. But it's another story.

I am closing this issue as the original problem seems to be resolved.