Performance on startup. all previous content reset

I started this up from two weeks back on 18w18b if I recall. This was the snapshot where the drowned was fixed and the lava color was restored. Upon startup, it took forever to load - indicating it was "Spawning Area". What gives?

 

I then see myself with my items in hand but around me is nothing but sand and water. Where my house? Where's my items in my chests? Where's my Nether portal?