There appears to be a bug when manually adding a weigh-in to weight history.
If I update my weight on the correct date of the weigh in it appears with the correct date on the weight history tab. However, if I forget on the date, but want to add it retroactively, I have to select the date AFTER the date of the weigh-in for it to appear with the correct date in the history list. This is, if on March 10 I want to enter a weigh-in for March 8, I need to select March 9 in the calendar when adding the entry in order for it to appear as March 8 in the weigh-in history list.