src/Strata.SqlTools.Snowflake/ExpressionFactory/Query/CalculationFilterGroup.cs

@@ -29,6 +29,6 @@ public class CalculationFilterGroup
 
     public bool IsValid()
     {
-        return GetValidFilters().Any();
+        return Filters != null && Filters.Any(x => x.IsValid());
     }
 }

src/Strata.SqlTools.Snowflake/ExpressionFactory/Query/QueryConfigExtensions.cs

@@ -13,6 +13,7 @@ public static class QueryConfigExtensions
         return queryConfig.Values.SelectMany(value => value.CalculationDataColumnIds)
             .Union(queryConfig.Values.SelectMany(x => x.FilterGroups.SelectMany(y => y.GetValidFilters().Select(f => f.DataColumnId))))
             .Union(queryConfig.Rows.Select(row => row.DataColumnId))
+            // FilterGroup.Filters is pre-filtered at construction (see FilterGroup.cs JsonConstructor); no GetValidFilters() equivalent is needed here.
             .Union(queryConfig.FilterGroups.SelectMany(filterGroup => filterGroup.Filters.Select(filter => filter.DataColumnId)))
             .ToArray();
     }

src/Strata.SqlTools.SqlServer/ExpressionFactory/Query/CalculationFilterGroup.cs

@@ -29,6 +29,6 @@ public class CalculationFilterGroup
 
     public bool IsValid()
     {
-        return GetValidFilters().Any();
+        return Filters != null && Filters.Any(x => x.IsValid());
     }
 }

src/Strata.SqlTools.SqlServer/ExpressionFactory/Query/QueryConfigExtensions.cs

@@ -13,6 +13,7 @@ public static class QueryConfigExtensions
         return queryConfig.Values.SelectMany(value => value.CalculationDataColumnIds)
             .Union(queryConfig.Values.SelectMany(x => x.FilterGroups.SelectMany(y => y.GetValidFilters().Select(f => f.DataColumnId))))
             .Union(queryConfig.Rows.Select(row => row.DataColumnId))
+            // FilterGroup.Filters is pre-filtered at construction (see FilterGroup.cs JsonConstructor); no GetValidFilters() equivalent is needed here.
             .Union(queryConfig.FilterGroups.SelectMany(filterGroup => filterGroup.Filters.Select(filter => filter.DataColumnId)))
             .ToArray();
     }