I recently posted a bug stating ores placed in inventory blocks will disappear after leaving a world, and player inventories are unaffected. Please disregard that specific report. Player invetories are in fact affected, and it's happening to more than just ores. I'm posting this new one cause I figured a new post would fix more than just what was initially said, as what's happing is broader than what was first though. What hasn't changed is that some mined ores will not only disappear from said inventories, but occasionally will regenerate where they originally were. It's only a small chance, and only a small amount mined will regen if it does happen.