You sure you did warlock & titan? According to your collections, only your hunter has the Solstice ornament set.
Hi there. You may have accidentally refunded the package on the Warlock. If so, there's nothing that can be done as that item is no longer available in the Eververse Store. If you're sure you opened the package, you can contact Bungie via their Missing Eververse Item contact form: https://www.bungie.net/en/Help/Troubleshoot?oid=13681