When loading into a current world, I noticed missing inventory, specifically iron, diamonds, rails, coal and redstone to name a few. Some reloads will result in partial missing inventory such as a 1/2 loss of specific items to a full loss of specific items.

To recreate issue.  Exit current game, quit Minecraft and reload reload Minecraft, reload game and check inventory. This will work best when items are placed in the lowest righthand position of the inventory chest. These items will disappear 100% of the time.

Method of testing.  Repeated reloading of worlds and noting missing items. Testing was done by reloading 3 different worlds with same results, partial or completely missing inventory. Diamonds, iron, coal blocks and basic rails seem to be most affected.

Importance. High. I am enrolled in the current bedrock beta version Xbox 1 and understand that bugs are expected as part of the game development, this is a major issue that seriously impedes gameplay and requires reporting. 

Thank you for your time.