403 Forbidden error when creating vector index Opensearch Serverless

I want to create a bedrock agent with a knowledge base. For the knowledge base I have to use Opensearch. So, I created an opensearch serverless collection and I need to create a vector index and vector fields. I have to do it as code, so I tried to search how to create it and I found that I could only use an API call to the endpoint provided by the collection. So I tried to call the endpoint like in this guide:

[PUT] https://xyz.us-east-1.aoss.amazonaws.com/housing-index

Body:

{
   "settings": {
      "index.knn": true
   },
   "mappings": {
      "properties": {
         "housing-vector": {
            "type": "knn_vector",
            "dimension": 3
         },
         "title": {
            "type": "text"
         },
         "price": {
            "type": "long"
         },
         "location": {
            "type": "geo_point"
         }
      }
   }
}

But it returns me this error

{
	"status": 403,
	"request-id": "xyz",
	"error": {
		"reason": "403 Forbidden",
		"type": "Forbidden"
	}
}

So it tried to create it in the console, and it worked. Then i tried in the opensearch dashboard, and it worked. And the problem isn't the way I call the api, because I use my aws credentials in Insomnia and call it. I even has a successful response when doing this call:

https://xyz.us-east-1.aoss.amazonaws.com/index-created-in-console

And the problem isn't the permissions because I have the AdministratorAccess, and gave me all the permissions I could (Data access policies, Encryption policies, Network policies, ...).

I tried a lot of bodies: in JSON, Plain, other, ... With and without the PUT housing-index in it.

If anyone could help me I would be grateful.