The measure is "Screening for Depression" in MAT staging.

The following definition is returning a validation error which was not showing up prior to the most recent MAT staging update.

define "Most Recent Adult Depression Screening":
Last (["Assessment, Performed": "Adult Depression Screening"] Adultscreen
with "Depression Screening Encounter" Enc
such that Adultscreen.authorDatetime during Enc.relevantPeriod and Adultscreen.result is not null
sort by Adultscreen.authorDatetime)

If I remove "sort by Adultscreen.authorDatetime" the definition saves without error.

for reference the other definition used is -
define "Depression Screening Encounter":
["Encounter, Performed": "Depression Screening Encounter Codes"] Enc
where Enc.relevantPeriod during "Measurement Period"