Appeared in different location after saving and later reloading.

When I reloaded the game I appeared in a significantly different location than where I was when I last saved. The location I reappeared in was probably at least 16 blocks away from the save position, and it was "inside" a building (mob capture system) that has no entrance.

Playing on a realm, but this is not a "rollback" issue as everything else was unchanged and I had not been inside the building where I appeared for months.