After joining my friends Realm that I had previously been playing earlier in the day, I was surprised to find my character at the world's spawn. At first I thought maybe I somehow died after exiting the realm but I found a map in my inventory, an obvious characteristic of a new player to a realm. I travel a couple thousand blocks to our main base and even my enderchest data link to my character was wiped clean so it's obvious that my character data got wiped. I then had a friend sign in and his data was normal and he still had everything. I can't imagine that there is anything Mojang can to to get my data back but it would be nice to have this error fixed in the future so it doesn't effect anyone else.