Unable to add a Vectorizer to ragindex on the Search service

[framigni]

In the Search service search0-pp74jmspzstpu, ragindex, in Vector profiles, profile myHnswProfile, there is no Vectorizer.
It looks that Indexes with a Vectorizer perform much better, so we tried to add a new Vectorizer to the myHnswProfile. It can be added, but it cannot be saved (not clear the reason, maybe because the way it has been deployed ?)
We tried then to add a new Profile, but that also cannot be saved.
Finally, we tried to add a new Index with a Vectorizer, and change the Orchestration Function to deal with the new Index rather than ragindex, but the RAG stops working, it fails to retrieve from the data source.
Any information about all above would be great