Spawned at world spawn with no inventory or ender chest items, but reverted to normal after loading world a second time.

I opened my Minecraft world and suddenly found myself at the world spawn with nothing in my inventory. I walked back to where my base was and when I opened my ender chest, nothing was there either. Many of the items I had recently collected and put in chests were also missing. I tried to remake the items, but I left and reentered the world. After reentering, I was actually where I was the last time I had played, nearly 10,000 blocks away from the world spawn, and all of my items had returned. When I returned to spawn, the items that went missing were also back. Everything I did while the world wasn't functioning normally also got erased.