I decided to create a new world on the Xbox One Bedrock edition. I loaded the world into the 1.16 beta and played for around a week until I had full Netherite gear, I proceeded to enchant the tools. My Pickaxe has Unbreaking 3, Fortune 3, Efficiency 5 and Mending 1, all of which are in that order and were put on using an Anvil and enchanted book gained from villager trades. I have been mining naturally for about five hours and collected around 40 diamond ore  all of which were mined with my Netherite Pickaxe with the enchantments below and I gained exactly the same amount of diamonds as ore mined which doesn’t occur while using fortune 3. I then switched to a Diamond Pickaxe with fortune 3 and was gaining 3-4 diamonds from each ore. I am assuming this is a bug as I have done many hours of testing and it always comes to the same conclusion.