You’re authoring in Power Query. You decide that rows with 0001-01-01 in a certain column should be removed, so you filter on the column, excluding 0001-01-01 values. After you apply your filter, nothing changes: the 0001-01-01 rows are still present. What is going on?

This issue bit me recently. Turns out, it’s due to a translation loss when bridging between the worlds of MySQL and Power Query.