Important note: I am reporting this for a friend, I have not experienced this on my own device.

When my friend opened their world, they were at their spawn with no items. This has happened multiple times and seems to be random. They lost a lot of progress as they had not made any world or item backups. This was not fixed by leaving and rejoining. The device is new, and it has not happened on their old one, so it may be a device issue.