Best way to model inventories

[Javierco]

Probably missing something very basic about how measures work. 

I have a measure to calculate inventory on hand based on table inventory_v2.

When reporting a table for August I get:

When reporting September, I get:

Both tables seem to be ok. However when I select both months, I get:

which shows data from both months, but when calculating totals only considers September data.

The expected result would have been to get a table identical to September since it is the latest month.

Would much appreciate your help in understanding why the difference vs expected and should I modify my measures to get the expected result.

Some additional info:

"label" column is a calculated column based on inventory price

Inventory on hand is calculated as follows:

inv_on_hand_v5 = 

VAR latest_date = CALCULATE(MAX(inventory_v2[inventory_date]))
VAR inv_currency = CALCULATE(SUMX(inventory_v2,(inventory_v2[inventory_amount]) / inventory_v2[relatedrate]), FILTER((inventory_v2),latest_date==inventory_v2[inventory_date]))
VAR inv_units = CALCULATE(SUMX(inventory_v2,(inventory_v2[inventory_qty])), FILTER((inventory_v2),latest_date==inventory_v2[inventory_date]))

RETURN inv_currency

[andhiii079845]

This is the typical "total sum" problem with dax:
https://www.sqlbi.com/articles/why-power-bi-totals-might-seem-inaccurate/
YOU can fix it like this:

RETURN if(hasonefilter(label)=TRUE;inv_currency;X)

The problem can be that you choose with 

latest_date = CALCULATE(MAX(inventory_v2[inventory_date]))

only the last date in sept  in the last row. 

One idea:

inv_on_hand_v5 = 
VAR earlist_date = CALCULATE(MIN(inventory_v2[inventory_date]))
VAR latest_date = CALCULATE(MAX(inventory_v2[inventory_date]))
VAR inv_currency = CALCULATE(SUMX(inventory_v2,(inventory_v2[inventory_amount]) / inventory_v2[relatedrate]), FILTER((inventory_v2),latest_date>=inventory_v2[inventory_date])&& earlist_date<=inventory_v2[inventory_date]))
VAR inv_units = CALCULATE(SUMX(inventory_v2,(inventory_v2[inventory_qty])), FILTER((inventory_v2),latest_date==inventory_v2[inventory_date]))

RETURN inv_currency