It is almost always something in the title or description that automatically reports the listing as "not shippable". Categories like Furniture, motorcycles. etc wont show shipping option. Scan your details and anything that sounds like furniture or other large item, remove and replace the word or words. Sometimes i manipulate it for items that may say "table" or something in description, but is not a table and "write ta ble". It usually works. You can test it by trying simply FOR SALE and see if shipping appears.
This is why "shipping" should NOT be the default setting when posting items.