Measure acts different when combined

Hi guys,

I have written this code to calculate the latest balance per week. When i plot the measure it works as i intended; when there is no new data, it takes the last balance and puts it through till the end of the year, like this (there is only data till week 20).

However, when i combine this with 2 other measures, it acts differently and stops till when there is no data, like this:

Do you guys have an idea what might be causing this?