Missing/ deleted items from shulker box

Hi 

I am using Windows 8.1 64 bit and the latest Java download. I am having trouble with lost items in my shulker boxes I just loaded into the 18w47b and a few of my shulker boxes have empty inventories . 

I saved and quit my survival world to test something in my testing world. Then I left the testing world to go back to my survival world. Upon loading into my survival world I checked the contents of a shulker box I have right next to a build to find that it was empty.

 

I'm assuming that what should have happened is that the shulker's Items shouldn't have just vanished.