I am seeing the following in the log

Failed to create non existing workflow instance (Instance Id: 7c967e82-8bbe-41bb-90b1-794c0224fd6f) from HistoryEventReceiver: System.NullReferenceException: Object reference not set to an instance of an object.   

at Nintex.Workflow.Runtime.WorkflowInstance.DirectInsertWorkflowInstance(SPWorkflow workflow)   

at Nintex.Workflow.Features.WorkflowHistoryEventReciever.ItemAdded(SPItemEventProperties properties) (Build:3130)

: Nintex.Workflow.NWException: Workflow schedule failed. Schedule details can be viewed at: https://tdwiki.tdindustries.com/content/_layouts/15/NintexWorkflow/NewWorkflowSchedule.aspx?ListId={00000000-0000-0000-0000-000000000000}&ItemId=-1&ScheduleId=74 ---> System.Reflection.TargetInvocationException: Exception has been thrown by the target of an invocation. ---> System.NullReferenceException: Object reference not set to an instance of an object.   

at Microsoft.SharePoint.Workflow.SPWinOeHostServices.EnsurePluggableServices(SPSite site, SPWorkflowExternalDataExchangeServiceCollection services, ExternalDataExchangeService existingServices)   

at Microsoft.SharePoint.Workflow.SPWinOeHostServices..ctor(SPSite site, SPWeb web, SPWorkflowManager manager, SPWorkflowEngine engine)     -

-- End of inner exception stack trace ---   

at System.RuntimeMethodHandle.InvokeMethod(Object target, Objecte] arguments, Signature sig, Boolean constructor)   

at System.Reflection.RuntimeConstructorInfo.Invoke(BindingFlags invokeAttr, Binder binder, Objecti] parameters, CultureInfo culture)   

at System.RuntimeType.CreateInstanceImpl(BindingFlags bindingAttr, Binder binder, Objectg] args, CultureInfo culture, Objectt] activationAttributes, StackCrawlMark& stackMark)   

at System.Activator.CreateInstance(Type type, BindingFlags bindingAttr, Binder binder, Objectg] args, CultureInfo culture, Objectb] activationAttributes)   

at System.Reflection.Assembly.CreateInstance(String typeName, Boolean ignoreCase, BindingFlags bindingAttr, Binder binder, Objectn] args, CultureInfo culture, Objectr] activationAttributes)   

at Microsoft.SharePoint.Workflow.SPWorkflowManager.LoadPluggableClass(String classname, String assembly, Objectl] parameters)   

at Microsoft.SharePoint.Workflow.SPWorkflowManager.GetService(SPWorkflowAssociation association, SPWorkflowEngine engine)   

at Microsoft.SharePoint.Workflow.SPWorkflowManager.RunWorkflowElev(SPWorkflow workflow, Collection`1 events, SPWorkflowRunOptionsInternal runOptions)   

at Microsoft.SharePoint.Workflow.SPWorkflowManager.StartWorkflowElev(Object context, SPWorkflowAssociation association, DateTime elevationTimeUtc, SPWorkflowEvent startEvent, SPWorkflowRunOptions runOptions)   

at Microsoft.SharePoint.Workflow.SPWorkflowManager.<>c__DisplayClass16.<StartWorkflow>b__15(SPSite superUserSite, SPWeb superUserWeb)   

at Microsoft.SharePoint.SPSecurity.<>c__DisplayClassd.<RunWithSystemSiteAndWeb>b__b()   

at Microsoft.SharePoint.SPSecurity.<>c__DisplayClass5.<RunWithElevatedPrivileges>b__3()   

at Microsoft.SharePoint.Utilities.SecurityContext.RunAsProcess(CodeToRunElevated secureCode)   

at Microsoft.SharePoint.SPSecurity.RunWithElevatedPrivileges(WaitCallback secureCode, Object param)   

at Microsoft.SharePoint.SPSecurity.RunWithElevatedPrivileges(CodeToRunElevated secureCode)   

at Microsoft.SharePoint.Workflow.SPWorkflowManager.StartWorkflow(Object context, SPWorkflowAssociation association, SPWorkflowEvent startEvent, SPWorkflowRunOptions runOpts)   

at Microsoft.SharePoint.Workflow.SPWorkflowManager.StartWorkflow(Object context, SPWorkflowAssociation association, String eventData, SPWorkflowRunOptions runOptions)   

at Nintex.Workflow.Scheduling.WorkflowScheduleItem.Execute()   

at Nintex.Workflow.Scheduling.WorkflowSchedulerJob.Execute(Guid targetInstanceId)     -

-- End of inner exception stack trace --- (Build:3130)