Mysteriously, my weight has stopped appearing on the My Day screen. I can enter weight on the My Day screen, and it clearly gets stored as the full history is there in More->Health Stats. However, it's mysteriously disappeared from My Day and toggling it on and off in the cards there doesn't seem to make any difference.
Not sure whether this was an issue that popped up when the app updated to 4.3.1 or not but timing of the error would suggest that is possible.