I was playing today on my phone using my Xbox controller (as I play console aswell) on my lunch break at work. I had a valuable enchanted netherite pickaxe in hand in my hotbar when I saved and quit my game, I then logged back in a few hours later on my next break to find it's disappeared. I know for certain I haven't dropped it on accident cause it's not something you drop and not notice, also reading through the other bugs people have listed it seems to be a common bug with items disappearing. Is also on a friends realm if it makes any difference.