Unable to retrieve a "call" I made using the Test My Knowledge Base UI

Unfortunately, there is no built-in feature in the Amazon Bedrock console to retrieve or access the history of previous test queries and responses for a knowledge base. The Test Knowledge Base functionality in the console is designed for immediate testing and does not maintain a persistent history of queries and responses.

When you navigate away from the test window or change pages, the previous test results are not saved or accessible. Each time you open the test window, you start with a fresh session.

To maintain a record of your test queries and responses, you would need to manually save or copy the information before navigating away from the test window. Alternatively, you could consider using the API methods for querying your knowledge base, which would allow you to programmatically store and retrieve your query history.

While it would indeed be convenient to have access to previous test responses, especially in cases of accidental page changes, this feature is not currently available in the Amazon Bedrock console interface for knowledge base testing.
Sources
Query a knowledge base and retrieve data - Amazon Bedrock
Test your knowledge base with queries and responses - Amazon Bedrock