All shulker box contents disappeared in minecraft preview in the x box

This is my son that this happened to, it is his birthday tomorrow and he is very upset, he has lost I don’t know how many items so please help anyway he was playing Minecraft Preview on Xbox in a Survival world.

I had several Shulker Boxes stored inside my Ender Chest. The Shulker Boxes contained valuable items collected during normal Survival gameplay, including my Dragon Egg, Silence Armor Trim and many other items.

When I opened my Ender Chest, the Shulker Boxes themselves were still present and other items stored directly in the Ender Chest were also still present. However, when I opened the Shulker Boxes, every Shulker Box was completely empty. All items previously stored inside them had disappeared.

Steps to reproduce / circumstances:

1. Play a Survival world in Minecraft Preview on Xbox.

2. Place items inside multiple Shulker Boxes.

3. Store those Shulker Boxes inside an Ender Chest.

4. Save/leave the world and later reload it.

5. Open the Ender Chest and then the Shulker Boxes.

Expected result:
The Shulker Boxes should retain all items stored inside them.

Actual result:
The Shulker Boxes remain in the Ender Chest, but all of their contents have disappeared. Other items stored directly in the Ender Chest remain intact.

This affected every Shulker Box I checked, resulting in the loss of numerous Survival items.