Async response enabled in agent flow, flow completes but agent does not return final response

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Posted on by VB-03020721-0

Hi Everyone,

I am testing the new asynchronous responses for agent flows feature in Copilot Studio to allow long-running flows to exceed the normal timeout and return the result when completed.

I followed the Microsoft documentation for asynchronous agent flow responses and verified that the environment meets the required environment conditions.

Setup:

Created an agent in Copilot Studio.
Added a flow as a tool.
Flow starts with When an agent calls the flow.
Inside the flow, I added Execute Agent and wait (Microsoft Copilot Studio).
Final action is Respond to the agent.
Enabled Asynchronous response on the Respond to the agent action.

Observed behavior:

When testing from the Copilot Studio test pane:

The agent successfully invokes the flow.
The flow runs for more than the normal timeout limit.
Because async response is enabled, the flow does not fail with timeout.
The Execute Agent and wait action completes after around 5 minutes.
The Respond to the agent action also completes successfully.
However, the agent never sends the final response back to the user.

During the wait, the agent only says that it successfully called the flow and will return the response later, but no final response is received.

I also tested the same agent from Teams and the Microsoft 365 Copilot app, but the result is the same.

This behavior looks similar to the documentation section for immediate responses, where removing Respond to the agent makes the agent respond immediately after triggering the flow. But in my case, I have kept Respond to the agent and enabled async response because I need the final result returned after the long-running flow completes.

My questions are:

Is any additional setting required at the agent, channel, flow, or environment level for async flow responses to return the final message?
Is async response currently supported when the flow contains Execute Agent and wait inside it?
Is this supported in the Copilot Studio test pane, Teams, and Microsoft 365 Copilot channels?
Is there any known limitation where the flow completes successfully but the final async response is not delivered back to the conversation?
Is the final response expected to appear in the same conversation automatically, or does it require another message/user interaction?

Please correct me if I have misunderstood anything, or if there is a supported implementation pattern that I may be missing.

Categories:

Calling actions from Copilot Studio

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Valantis 6,735 on at

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Hi @VB-03020721-0,

Found the exact answers in Microsoft docs. Several things are confirmed here.

On your specific channels: <strong>callbacks (async responses) are not supported for Microsoft 365 Copilot.</strong> Microsoft docs explicitly state: "The callback feature for asynchronous flows is fully supported in Microsoft Teams. Other channels might also support callbacks, but they aren't formally tested. Callbacks aren't supported for Microsoft 365 Copilot and telephony channels."

This explains why the response never comes back in M365 Copilot chat. Try testing in Teams only, that's the confirmed supported channel.
On the Copilot Studio test pane: this isn't listed as a supported channel for async callbacks either, which may explain the test pane also not returning the final response.

On your Execute Agent and wait action inside the flow: Microsoft docs don't list this as a supported or tested pattern inside async flows. Standard async flow pattern is: When an agent calls the flow → long-running actions → Respond to the agent (with async enabled). Adding Execute Agent and wait inside that may be creating an unsupported nested async pattern.

Recommended approach: test the async response in Teams channel only (not M365 Copilot, not test pane), and remove Execute Agent and wait from inside the flow if possible. If you need to call another agent, do that at the Copilot Studio topic level, not inside the async flow.

Ref: https://learn.microsoft.com/en-us/microsoft-copilot-studio/flow-asynchronous-response

Best regards,

Valantis

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11manish 3,333 on at

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Based on your description, your implementation appears correct. The flow is successfully running asynchronously and completing, but the

callback response is not being surfaced back to the conversation. The most likely explanations are:

A current limitation or bug in the asynchronous response feature.

An unsupported scenario involving Execute Agent and wait inside an asynchronous agent flow.

A rollout gap where the backend completes the flow but does not yet deliver the final conversation callback reliably across channels.

I would recommend testing with a minimal async flow (without Execute Agent and wait) to determine whether the issue is with the feature

generally or specifically with the nested agent execution pattern. If the simplified scenario also fails, opening a Microsoft support ticket with run

history IDs and conversation IDs would be the next step, as the behavior does not match the documented expectation for asynchronous

responses.

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