SYMPTOM:
The sort parameter of the "Lag" function is removed from the metric definition after clicking on validate button in metric editor, as shown below:
CAUSE:
This behavior is by design. The sort parameter is still defined in the metric but just doesn't show up in the definition.
ACTION:
Highlight the "Lag" function -> Right click on "Lag" -> Lag parameters -> Go to "Sort By" tab. The sort parameter shows up here:
