Issue
Timeouts can occur when end-users take longer than usual to submit a form, such as one with many fields. This then displays the message The action has been cancelled because the timeout delay has expired even though there is no session-related timeout, and no errors appear in the process logs.
Solution
This error is usually raised when the user has exceeded the allowed time for completing an action, due to the data locking feature. For concurrency purposes, WorkflowGen locks the data to prevent other actions from overwriting their values. EngineDataProtectionLockTimeout is applied when there are OUT parameters in the current action (e.g. an action that returns a value to a process data). If an action has no OUT parameters, then no data lock error is raised.
The delay is controlled by the web.config parameter below. Try increasing the value to 10 minutes and see if this helps.
You can also change the parameter value in the Configuration Panel. In the Request section of the Portal tab, set Request data lock timeout for concurrent applications (minutes) to 10.