I couldn`t replicate this in flat world, placed over 4K sand blocks. I re-created my world in creative mode and this happened after I placed just few sand blocks.
After that I loaded my world and managed to record this video
This is happened in local singleplayer game
Here`s a video. You can see player hand movement changes too when it slows
I had crash issue with win10 edition.. every time when i open menu game crashed. But now it`s working..
System info