Agent block in multistep loop always returns PENDING even with sync mode configured

💬 App Building
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Issue: Agent blocks inside a multistep loop subflow return { agentRunId, agentId, status: "PENDING" } regardless of how sync mode is configured. This causes all downstream blocks in the subflow to run with no usable data.

Steps I've taken to troubleshoot:

  • Toggled "Result (sync)" in the UI — confirmed this doesn't stick. agentQueryMode reverts to "gui" every time the block is edited and saved.

  • Manually patched the JSON export to set all four sync-related fields: agentQueryMode: "workflow", agentWorkflowRunMode: "sync", workflowRunExecutionType: "sync", executionMode: "sync" — confirmed via re-export that all four are set correctly, still returns PENDING.

  • Tested multiple agentInputs formats: plain string, structured object, and { action: "invoke", messages: [{ role: "user", content: "..." }] } — same result regardless.

Additional info:

  • Retool Cloud

  • Workflow type: Multistep loop → function/subflow → Invoke Agent block

Has anyone gotten sync agents working inside a multistep loop subflow? Is it supported in that context, or only at the top level of a workflow? Any workarounds appreciated.

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@mco Hello Marcus, welcome to the Community! It was great connecting at Office Hours on Tuesday! I've flagged this with our engineering team. We have an internal ticket tracking this and I'll keep you posted as soon as there are updates!