BarChart displaying incorrect bars and doesn't stack value, just percentages instead

I have a BarChat that displays disk information from a series of servers, it basically displays the total disk size and the current free space.

My BarChart displays the results with discrepancies, very noticeable for the servers with 128GB disks, all the bars are displayed with different sizes, shouldn’t they all have the same width?

My second question is when I try to work with 100% stacked bars, the values are gone and instead I get percentages (which is not useful in my case):

Is it possible to get 100% stacked with the actual values like in the first example?