Boxes Disappearing From End Spawn

While playing on my wife's Realm account (ADKZ Family Realm, Backedcrayon163); we just finished a Wither fight in the End. As we were rebuilding from the devastation that unfolded. I had placed my Ender chess and a few Shulker Boxes on the Obsidian spawning pad. During reconstruction, we found that the my items disappeared from the pad. No matter what we tried to reload the area, it did not reappear. Can you help?