Knowledge base select model: Why The Model Providers always loading ?

Hello.

The model you select on that screen is not the model you want to embed in the vector store, but rather the model you want to use to generate the response after retrieving information from the knowledge base.
Therefore, the models that can be used are listed in the document below.
"Cohere Embed" is an embedded model of the vector store, so it cannot be selected from that screen.
The only models that can be selected on that screen are those in the table in the image below.
Therefore, if you enable model access such as "Anthropic Claude 3 Sonnet", you will be able to select the model on that screen.
https://docs.aws.amazon.com/bedrock/latest/userguide/knowledge-base-supported.html