I left my game running while afk to get my iron farm to produce the iron I needed for a project. In the same loaded area is my sugarcane farm that has a hopper minecart underneath the sugarcane running in an infinite loop. Hopper minecart has dissapeared twice now. First time I ended up having to rebuild the entire planting zone to get to the tracks to place another minecart. Second time I had built in an easy way for me to see if there was a minecart running and access a powered rail to place a new one.  I have not left the loaded zone via nether portal or end portal and I do not believe that I have had any game crashes recently since I saw that there were other open issues with that happening with a game crash.