I've been playing on my Nintendo Switch and when logging onto my survival worlds, sometimes I enter the world already dead with the entirety of my inventory lost, even when returning to where I died the items are gone, it's become quite an issue in Survival losing items such as a Fully enchanted Diamond Sword and set of Armour, and countless other things, the issue could be when logging on the game doesn't process the spawn location and will the kill the player trying to correct it. One solution is either to go into the code and see what issue needs to be resolved or to remove Gamerule; KeepInventory from preventing achievements as most players already play with it on almost religiously and if kids find the game too hard it might keep them in the game, Thanks for understand.
-Long Time Fan