With this PL/SQL you can find which records on your DCS_PRD_CHLDSKU table are missing a sequence, is is an edge case, but when it happens you need to go and find them and fix them otherwise your deployment will be stuck, this will help you to do it for all your products.

findBorkenSequenceChildSkus.sql

DECLARE
  CURSOR c_get_all_products
  IS
    SELECT DISTINCT(product_id) FROM DCS_PRD_CHLDSKU;
  seq_max      NUMBER;
  seq_count    NUMBER;
  broken_count NUMBER;
BEGIN
  broken_count := 0;
  FOR product_id IN c_get_all_products
  LOOP
    SELECT COUNT(*)
    INTO seq_count
    FROM DCS_PRD_CHLDSKU
    WHERE PRODUCT_ID = product_id.product_id
    ORDER BY SEQUENCE_NUM;
    SELECT MAX(SEQUENCE_NUM) + 1
    INTO seq_max
    FROM DCS_PRD_CHLDSKU
    WHERE PRODUCT_ID = product_id.product_id
    ORDER BY SEQUENCE_NUM;
    IF seq_max <> seq_count THEN
      DBMS_OUTPUT.PUT_LINE(product_id.product_id || ' seq_count=' || seq_count || ' seq_max=' || seq_max);
      broken_count := broken_count + 1;
    END IF;
  END LOOP;
  DBMS_OUTPUT.PUT_LINE(broken_count || ' records have broken sequence');
END;