Why did I wait too long to select model providers on Knowledge-bases on Amazon Bedrock ?

Hi I try Knowledge-bases on Amazon Bedrock and I enable "Generate Response" option so that I can run a query to generate responses without seeing vector store.

But Popup page that allow me to select model provider , it take very long to list model provider , as a result I can not continue. as figure below What was wrong with it?

However , you can run query to get result by disabling "Generate Response" as below I don't want this way.