diff --git a/src/modules/Elsa.MongoDb/Common/MongoDbStore.cs b/src/modules/Elsa.MongoDb/Common/MongoDbStore.cs
index c070fd188..9c5c3b674 100644
--- a/src/modules/Elsa.MongoDb/Common/MongoDbStore.cs
+++ b/src/modules/Elsa.MongoDb/Common/MongoDbStore.cs
@@ -405,7 +405,7 @@ public class MongoDbStore<TDocument>(IMongoCollection<TDocument> collection, ITe
         if (typeof(Entity).IsAssignableFrom(typeof(TDocument)))
         {
             var tenant = tenantAccessor.Tenant;
-            var tenantId = tenant?.Id;
+            var tenantId = tenant?.Id.EmptyToNull();
             queryable = queryable.Where(x => (x as Entity)!.TenantId == tenantId);
         }
 
@@ -418,7 +418,7 @@ public class MongoDbStore<TDocument>(IMongoCollection<TDocument> collection, ITe
         var tenantId = tenant?.Id;
 
         if (document is Entity tenantDocument)
-            tenantDocument.TenantId = tenantId;
+            tenantDocument.TenantId = tenantId.EmptyToNull();
     }
 
     private void ApplyTenantId(IEnumerable<TDocument> documents)
@@ -429,7 +429,7 @@ public class MongoDbStore<TDocument>(IMongoCollection<TDocument> collection, ITe
         foreach (var document in documents)
         {
             if (document is Entity tenantDocument)
-                tenantDocument.TenantId = tenantId;
+                tenantDocument.TenantId = tenantId.EmptyToNull();
         }
     }
 }
\ No newline at end of file
diff --git a/src/modules/Elsa.MongoDb/Extensions/StringExtensions.cs b/src/modules/Elsa.MongoDb/Extensions/StringExtensions.cs
new file mode 100644
index 000000000..cc806f04a
--- /dev/null
+++ b/src/modules/Elsa.MongoDb/Extensions/StringExtensions.cs
@@ -0,0 +1,6 @@
+namespace Elsa.MongoDb.Extensions;
+
+public static class StringExtensions
+{
+    public static string? EmptyToNull(this string? value) => string.IsNullOrWhiteSpace(value) ? null : value;
+}
\ No newline at end of file