diff --git a/src/Altinn.App.Core/Features/Validation/ValidationAppSI.cs b/src/Altinn.App.Core/Features/Validation/ValidationAppSI.cs
index 6b470d90d..aa5c78e6d 100644
--- a/src/Altinn.App.Core/Features/Validation/ValidationAppSI.cs
+++ b/src/Altinn.App.Core/Features/Validation/ValidationAppSI.cs
@@ -238,24 +238,30 @@ public async Task<List<ValidationIssue>> ValidateDataElement(Instance instance,
                     messages.AddRange(layoutErrors);
                 }
 
-                // run Standard mvc validation using the System.ComponentModel.DataAnnotations
-                ModelStateDictionary validationResults = new ModelStateDictionary();
+                // Run Standard mvc validation using the System.ComponentModel.DataAnnotations
+                ModelStateDictionary dataModelValidationResults = new ModelStateDictionary();
                 var actionContext = new ActionContext(
                     _httpContextAccessor.HttpContext,
                     new Microsoft.AspNetCore.Routing.RouteData(),
                     new ActionDescriptor(),
-                    validationResults);
+                    dataModelValidationResults);
                 ValidationStateDictionary validationState = new ValidationStateDictionary();
                 _objectModelValidator.Validate(actionContext, validationState, null, data);
 
+                if (!dataModelValidationResults.IsValid)
+                {
+                    messages.AddRange(MapModelStateToIssueList(actionContext.ModelState, ValidationIssueSources.ModelState, instance, dataElement.Id, data.GetType()));
+                }
+
                 // Call custom validation from the IInstanceValidator
-                await _instanceValidator.ValidateData(data, validationResults);
+                ModelStateDictionary customValidationResults = new ModelStateDictionary();
+                await _instanceValidator.ValidateData(data, customValidationResults);
 
-                // Add the validation messages from System.ComponentModel.DataAnnotations and IInstanceValidator to the return list
-                if (!validationResults.IsValid)
+                if (!customValidationResults.IsValid)
                 {
-                    messages.AddRange(MapModelStateToIssueList(actionContext.ModelState, instance, dataElement.Id, data.GetType()));
+                    messages.AddRange(MapModelStateToIssueList(customValidationResults, ValidationIssueSources.Custom, instance, dataElement.Id, data.GetType()));
                 }
+
             }
 
             return messages;
@@ -263,6 +269,7 @@ public async Task<List<ValidationIssue>> ValidateDataElement(Instance instance,
 
         private List<ValidationIssue> MapModelStateToIssueList(
             ModelStateDictionary modelState,
+            string source,
             Instance instance,
             string dataElementId,
             Type modelType)
@@ -282,7 +289,7 @@ private List<ValidationIssue> MapModelStateToIssueList(
                         {
                             InstanceId = instance.Id,
                             DataElementId = dataElementId,
-                            Source = ValidationIssueSources.ModelState,
+                            Source = source,
                             Code = severityAndMessage.Message,
                             Field = ModelKeyToField(modelKey, modelType)!,
                             Severity = severityAndMessage.Severity,
diff --git a/src/Altinn.App.Core/Models/Validation/ValidationIssueSource.cs b/src/Altinn.App.Core/Models/Validation/ValidationIssueSource.cs
index 00d493a11..532119033 100644
--- a/src/Altinn.App.Core/Models/Validation/ValidationIssueSource.cs
+++ b/src/Altinn.App.Core/Models/Validation/ValidationIssueSource.cs
@@ -20,5 +20,10 @@ public static class ValidationIssueSources
         /// Required field validation
         /// </summary>
         public static readonly string Required = nameof(Required);
+
+        /// <summary>
+        /// Required field validation
+        /// </summary>
+        public static readonly string Custom = nameof(Custom);
     }
 }