diff --git a/application/CohortManager/src/Functions/Shared/Data/Database/ValidationExceptionData.cs b/application/CohortManager/src/Functions/Shared/Data/Database/ValidationExceptionData.cs
index 218085730..b009f6eee 100644
--- a/application/CohortManager/src/Functions/Shared/Data/Database/ValidationExceptionData.cs
+++ b/application/CohortManager/src/Functions/Shared/Data/Database/ValidationExceptionData.cs
@@ -347,7 +347,7 @@ private static List<ValidationException> SortExceptions(SortOrder? sortOrder, IE
 
     private async Task<List<ValidationException>> GetValidationExceptionsByNhsNumber(string nhsNumber)
     {
-        var exceptions = await _validationExceptionDataServiceClient.GetByFilter(x => x.NhsNumber == nhsNumber && x.Category == (int)ExceptionCategory.NBO);
+        var exceptions = await _validationExceptionDataServiceClient.GetByFilter(x => x.NhsNumber == nhsNumber && x.Category.HasValue && x.Category.Value == (int)ExceptionCategory.NBO);
         if (exceptions == null || !exceptions.Any())
         {
             return [];