Generally, when ranking or ordering a column that contains value NaN (Not a Number), you might get wrong or unexpected results. For example, when a calculation divides 0 by 0, an NaN result is returned. This is because the formula engine performs ordering
and ranking by comparing the numeric values; however, NaN cannot be compared to other numbers in the column. To assure correct results, you can use conditional statements using IF function to test for NaN values and return a numeric 0 value.
Based on the DAX your posted, it seems that the calculation in your scenario do not contain any divides 0 by 0. Please check other DAX query in your tabular model and ensure there is no any divides 0 by 0.
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