Data action executions are currently set to timeout at 20s through the Public API, and 60s through Architect/call flows. That said, 20s is an eternity when it comes to a REST API call, and it would be greatly discouraged regularly using a web services that takes that long to return a response. A better pattern would be to leverage an asynchronous API with a combination of data actions, where the first action requests the work and returns a reference number that can be passed to a second data action that requests the results (the second action can be retried multiple times while the Async process is trying to complete the request).
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Richard Schott
Genesys - Employees
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