List does not exist when trying to startworkflowonlistitem from CSOM

Using SharePoint 2013 on Windows Server 2012 Standard.

I believe this is an issue with permissions. When trying to start a workflow on a staging server, the following exception happens (as shown in UlsViewer).

Exception occured in scope Microsoft.SharePoint.WorkflowServices.WorkflowInstanceService.StartWorkflowOnListItem. Exception=System.ArgumentException:       List does not exist.      The page you selected contains a list that does not exist.  It may have been deleted by another user.       ---> Microsoft.SharePoint.Client.ResourceNotFoundException:       List does not exist.      The page you selected contains a list that does not exist.  It may have been deleted by another user.           -
 -- End of inner exception stack trace ---    
 at Microsoft.SharePoint.SPListCollection.ItemByInternalName(String strInternalName, Boolean bThrowException)    
 at Microsoft.SharePoint.SPListCollection.GetListById(Guid uniqueID, Boolean bThrowException)    
 at Microsoft.SharePoint.WorkflowServices.FabricWorkflowInstanceProvider.StartWorkflowOnListItem(WorkflowSubscription subscription, Int32 itemId, IDictionary`2 payload)    
 at Microsoft.SharePoint.WorkflowServices.WorkflowInstanceServiceServerStub.StartWorkflowOnListItem_MethodProxy(WorkflowInstanceService target, XmlNodeList xmlargs, ProxyContext proxyContext)    
 at Microsoft.SharePoint.WorkflowServices.WorkflowInstanceServiceServerStub.InvokeMethod(Object target, String methodName, XmlNodeList xmlargs, ProxyContext proxyContext, Boolean& isVoid)    
 at Microsoft.SharePoint.Client.ServerStub.InvokeMethodWithMonitoredScope(Object target, String methodName, XmlNodeList args, ProxyContext proxyContext, Boolean& isVoid)

The relevant code is the following:

var wfServicesManager = new WorkflowServicesManager(ctx, ctx.Web);
var workflowDeploymentService = wfServicesManager.GetWorkflowDeploymentService();
var wfSubscriptionService = wfServicesManager.GetWorkflowSubscriptionService();
var wfSubscriptions = wfSubscriptionService.EnumerateSubscriptions();
ctx.Load(wfSubscriptions, wfSubs => wfSubs.Where(wfSub => wfSub.Name == "Someuniqname"));
ctx.ExecuteQuery();
var wfSubscription = wfSubscriptions.First();
var wfInstanceService = wfServicesManager.GetWorkflowInstanceService();
var startParameters = new Dictionary<string, object>();
wfInstanceService.StartWorkflowOnListItem(wfSubscription, folioId, startParameters);
ctx.ExecuteQuery();

The IIS Application Pool is running as the same user account as the SharePoint App Pool, which happens to be a system account. I don't know if that could be an issue (I don't think so?), but just pointing it out.