Looks like some DL systems just haven't been updated yet as earnings became effective on 12/22 (see announcement below). As long as it's not a Basic Economy fare (purchased on/after 12/9), you will earn credit toward Medallion status. The MQM calculator reflects this when choosing ITA operated flights.

"Beginning with travel on December 22, 2021, SkyMiles Members can earn miles and earn towards Medallion Status on Delta-marketed, ITA Airways operated flights(1)."