Summary:

My friend and I play in 2 player mode on an XBox One using a world in my friend's local account. It's as if Minecraft alternates between 2 profiles for my account each time I play as 2nd player in my friend's world (i.e. save location, inventory, xp, etc) even though I use the same XBox account when I play.

Steps to reproduce:

My friend signs into the XBox One, starts Minecraft, and begins playing in the same world
we always play in. I then join the game on the same local XBox One as player 2. I choose my Xbox account to identify myself (I choose the same one every time).

The first time I noticed an issue I thought I had lost all my inventory, armor, xp, and save location after choosing my xbox account. It was as if I started as a 1st time player. However the next time I played it loaded the original profile and all my stuff was in my inventor, and my save location was correct. By "profile" I mean last save location, inventory, worn armor, xp, etc. This time I was worried to lose all my stuff so I put everything in a chest before saving and exiting. The next time I played I was surprised and grateful to see all my original inventory (from before the issue started). At this point I now always put all my stuff into a chest before playing (always as 2nd player in my friends world). 

It's as if Minecraft has 2 profiles for my account, and I don't know how to force it to use the same profile every time I play. (It's possible that I am seeing more than 2 profiles for my account, but without really testing it it seems like it's 2.) It also seems like it alternates between the 2 profiles each time I play, however I am sure that it alternates 100% of the time.

Other Notes:

We do not have XBox Gold and do not play online.

I don't know if the issue occurs in any of our other worlds. 

I don't know what Minecraft version that this issue started in as we had only recently started playing the old world again (from maybe 6 months ago).

 My friend always plays as player 1 (since it's their world) and they do not see the same issue, it's just me having the issue.