LangChain AWS: Streaming Not Working for Claude Sonnet 4 in Agent Mode (Bedrock)

[rpetchiappan]

I am using LangChain AWS (langchain_aws==0.2.29) with AWS Bedrock to run Anthropic Claude models in agent mode. My agent code streams responses correctly for Claude 3.7 Sonnet (us.anthropic.claude-3-7-sonnet-20250219-v1:0), but does not stream for Claude Sonnet 4 (us.anthropic.claude-sonnet-4-20250514-v1:0).
When I call the Bedrock converse stream API directly, Sonnet 4 streams as expected.
I am not passing the tool_choice parameter for Sonnet 4, per LangChain documentation.
Is there a limitation or bug in LangChain AWS for Sonnet 4 streaming in agent mode?
My agent code is generic and works for both models, but only Sonnet 3.7 streams.
Please advise if there is a workaround or if this is a known issue.
Thank you!