The map reads the top layer, witch is bedrock.
I have the same problem when I go to the nether and back. nothing else, just the nether. In survival.
Try to name it with a name tag next time
Maybe you are on ice, and you slide when flying.
It was almost the same for me, but no chunk error AND no cows spawning. NONE!!!!
Well, they ARE different dimensions, and the compasses and clocks and maps don't work. possibly as intended.