I have a workflow variable that tracks the SharePoint list item id from the Create SharePoint List item action, can it be retrieved using the Nintex Workflow Cloud API.
I’m referring to SharePoint Online.

Today, as I delved into the API, I managed to navigate through Actions and their specifics within failed instances. However, I hit a roadblock when trying to access variable values. Currently, the Nintex Workflow Cloud API doesn't offer access to Workflow Variables or the Output Variables of built-in actions, with the notable exception of text entries in the Workflow History Logs.

Fortuitously, the Workflow History Log actions provided an unexpected solution. By examining the SharePoint List Item Display form URLs logged in the Workflow History, I was able to identify the ListItem IDs generated by my workflow instances. To extract the relevant log messages, I used the following command:

$workflowHistoryLogMessage = $workflowInstance.Actions | Where-object {$_.id -eq $workflowLogActionId}

My script consisted of retrieving latest 100 workflow instances using below endpoint and iterating them for extracting specific details.

$uri = $BaseUri/workflows/v2/designs/$WorkflowId/instances?" + ($queryParams -join '&') 
$response = Invoke-RestMethod -Uri $uri -Method Get -Headers $Headers

Hope this helps someone who is experiencing similar issues and who would like to map their Workflow Instances to the ListItem Ids they are creating using workflow. 

Storing InstanceID in the ListItem properties could be helpful, I will consider it when I’m designing my future workflows.