Hi,
Currently if you want to get a serial number in the Workflow you have to use a workaround like https://community.nintex.com/nintex-automation-29/how-to-get-a-task-serial-number-in-the-workflow-27692
There is also a property called the "Serial number" in a context browser but this property isn't available for all the activities in a task scope. The property is available for a "SmartObject method" task but it isn't available for the "SetVariables" activity.
The idea is to make the "Serial number" property accesible for all the activities in a task scope.
Please vote on it :)
Kind regards,
Piotr