Power Bi / accounting question

Hello - Any accounting professionals out there that could answer this?  
I am well aware of how measure totals in Power Bi can sometimes give unexpected results, but not sure if this is the case here.  

We can see that the first 3 columns correctly added up, then the 4th column, which is correct at each row level, does not "add up" or even average to a number that might be expected at the total.    This is filtered to a particular family of products and within that two different product groups.  And the question is should that Margin % total be an average of the rows above it, or is it correctly stated as is?    The last two rows consist of a product group that for this particular month had 0% margin, and when filtered by themselves, correctly show 0%.    Likewise, the top three if filtered sepearately also show a correct "total" of 42.08%.    It is only when all show together, and the bottom total is being calculated, that the -4k % shows up.    I'm thinking it should probably show an average of the 4th column.