My Minecraft says version 1.99, and was recently updated with Bedrock, but that isn't given as an option. Regardless, today I attempted to break one of my shulker boxes to go adventuring and it disappeared. Vanished. All of my other boxes are also missing, but were stored away in my "goodies" chest and not placed in the world. I'm not sure if they were in the chest when I loaded my game or not.
Thank you for your report!
We're tracking this issue under MCPE-58812 so I've requested this report be resolved and linked as a duplicate.
If you would like to add a vote and any extra information to the main ticket it would be appreciated.
Quick Links:
📓 Issue Guidelines – 💬 Community Support – 📧 Customer Support – 📖 Game Wiki