My shulker boxes disappeared.

MY SHULKER BOXES FULL OF ITEMS KEEP DISSAPEARING!  Just finish farming for 4 hours and my entire shulker and all items that took me four hours to get are gone.  I play everyday but since this i dont want to play anymore.  Its the second time it happens.  The first time i lost 96 diamonds.  Please fix this so i can play again.  It seems to happen when transferring items from a shulker to a regular chest.  I grabbed the items from the shulker and as im putting items in the regular chest the game freezes.  No choice but to close app.  When i load back into my seed my shulker is gone as well as my items.  Im on the xbox version please help.