diff --git a/samples/aspnet/Elsa.Samples.AspNet.BatchProcessing/Workflows/OrderBatchProcessor.cs b/samples/aspnet/Elsa.Samples.AspNet.BatchProcessing/Workflows/OrderBatchProcessor.cs
index 42d727eb5..0ad44abf9 100644
--- a/samples/aspnet/Elsa.Samples.AspNet.BatchProcessing/Workflows/OrderBatchProcessor.cs
+++ b/samples/aspnet/Elsa.Samples.AspNet.BatchProcessing/Workflows/OrderBatchProcessor.cs
@@ -1,3 +1,4 @@
+using Elsa.Extensions;
 using Elsa.Samples.AspNet.BatchProcessing.Activities;
 using Elsa.Samples.AspNet.BatchProcessing.Models;
 using Elsa.Workflows;
@@ -14,7 +15,7 @@ public class OrderBatchProcessor : WorkflowBase
     /// <inheritdoc />
     protected override void Build(IWorkflowBuilder builder)
     {
-        var orders = builder.WithVariable<IAsyncEnumerable<ICollection<Order>>>();
+        var orders = builder.WithVariable<IAsyncEnumerable<ICollection<Order>>>().WithMemoryStorage();
         builder.Root = new Sequence
         {
             Activities =
diff --git a/src/modules/Elsa.Workflows.Api/Endpoints/WorkflowInstances/List/Endpoint.cs b/src/modules/Elsa.Workflows.Api/Endpoints/WorkflowInstances/List/Endpoint.cs
index 96bbed0c1..bbdb2a1b2 100644
--- a/src/modules/Elsa.Workflows.Api/Endpoints/WorkflowInstances/List/Endpoint.cs
+++ b/src/modules/Elsa.Workflows.Api/Endpoints/WorkflowInstances/List/Endpoint.cs
@@ -23,8 +23,12 @@ internal class List(IWorkflowInstanceStore store) : ElsaEndpoint<Request, Respon
     public override async Task HandleAsync(Request request, CancellationToken cancellationToken)
     {
         var pageArgs = PageArgs.FromPage(request.Page, request.PageSize);
+        var workflowStatuses = request.Statuses?.Any() == true ? ParseEnumStrings<WorkflowStatus>(request.Statuses).ToList() : null;
+        var workflowSubStatuses = request.SubStatuses?.Any() == true ? ParseEnumStrings<WorkflowSubStatus>(request.SubStatuses).ToList() : null;
 
-        if (!await ValidateInputAsync(request, cancellationToken))
+        ValidateInput(request);
+
+        if (ValidationFailed)
         {
             await SendErrorsAsync(StatusCodes.Status400BadRequest, cancellationToken);
             return;
@@ -39,8 +43,8 @@ internal class List(IWorkflowInstanceStore store) : ElsaEndpoint<Request, Respon
             CorrelationId = request.CorrelationId,
             WorkflowStatus = request.Status,
             WorkflowSubStatus = request.SubStatus,
-            WorkflowStatuses = request.Statuses?.Any() == true ? request.Statuses : null,
-            WorkflowSubStatuses = request.SubStatuses?.Any() == true ? request.SubStatuses : null,
+            WorkflowStatuses = workflowStatuses,
+            WorkflowSubStatuses = workflowSubStatuses,
             HasIncidents = request.HasIncidents,
             TimestampFilters = request.TimestampFilters?.Any() == true ? request.TimestampFilters : null,
         };
@@ -50,7 +54,21 @@ internal class List(IWorkflowInstanceStore store) : ElsaEndpoint<Request, Respon
         await SendOkAsync(response, cancellationToken);
     }
 
-    private async Task<bool> ValidateInputAsync(Request request, CancellationToken cancellationToken)
+    private IEnumerable<TEnum> ParseEnumStrings<TEnum>(IEnumerable<string> strings) where TEnum : struct
+    {
+        foreach (string s in strings)
+        {
+            if (Enum.TryParse<TEnum>(s, true, out var result))
+                yield return result;
+            else
+            {
+                AddError($"Invalid enum value '{s}'.");
+                yield break;
+            }
+        }
+    }
+
+    private bool ValidateInput(Request request)
     {
         if (request.Page is < 0)
         {
diff --git a/src/modules/Elsa.Workflows.Api/Endpoints/WorkflowInstances/List/Models.cs b/src/modules/Elsa.Workflows.Api/Endpoints/WorkflowInstances/List/Models.cs
index b37960763..4523df3c9 100644
--- a/src/modules/Elsa.Workflows.Api/Endpoints/WorkflowInstances/List/Models.cs
+++ b/src/modules/Elsa.Workflows.Api/Endpoints/WorkflowInstances/List/Models.cs
@@ -16,9 +16,9 @@ public class Request
     public int? Version { get; set; }
     public bool? HasIncidents { get; set; }
     public WorkflowStatus? Status { get; set; }
-    public ICollection<WorkflowStatus>? Statuses { get; set; }
+    public ICollection<string>? Statuses { get; set; }
     public WorkflowSubStatus? SubStatus { get; set; }
-    public ICollection<WorkflowSubStatus>? SubStatuses { get; set; }
+    public ICollection<string>? SubStatuses { get; set; }
     public OrderByWorkflowInstance? OrderBy { get; set; }
     public OrderDirection? OrderDirection { get; set; }
     public ICollection<TimestampFilter>? TimestampFilters { get; set; }
diff --git a/src/modules/Elsa.Workflows.Core/Activities/ParallelForEachT.cs b/src/modules/Elsa.Workflows.Core/Activities/ParallelForEachT.cs
index 07cee0097..d5d8fcd63 100644
--- a/src/modules/Elsa.Workflows.Core/Activities/ParallelForEachT.cs
+++ b/src/modules/Elsa.Workflows.Core/Activities/ParallelForEachT.cs
@@ -43,8 +43,10 @@ public class ParallelForEach<T> : Activity
         var items = context.GetItemSource<T>(Items);
         var tags = new List<Guid>();
         var currentIndex = 0;
-
-        // Iterate over the items.
+        
+        context.SetProperty(ScheduledTagsProperty, tags);
+        context.SetProperty(CompletedTagsProperty, new List<Guid>());
+        
         await foreach (var item in items)
         {
             // For each item, declare a new variable for the work to be scheduled.
@@ -62,10 +64,7 @@ public class ParallelForEach<T> : Activity
             tags.Add(tag);
             await context.ScheduleActivityAsync(Body, OnChildCompleted, tag, variables);
         }
-
-        context.SetProperty(ScheduledTagsProperty, tags);
-        context.SetProperty(CompletedTagsProperty, new List<Guid>());
-
+        
         // If there were no items, we're done.
         if (tags.Count == 0)
             await context.CompleteActivityAsync();