Currently getting this warning for all metahuman body types while packaging. Animations work fine in Editor and in Packaged Game.
The method used was simply assigning the base Skeletal Mesh Components of the metahuman (except the face) to the UE5 SK_Mannequin Base Skeleton. Any information on what exactly these warnings mean, possible fixes, or alternative/correct methods of retargeting is much appreciated!
Method used is shown in this video:
Youtube: Replace Character with Metahuman in UE5. IK foot issue solved.
UPDATE: Went through the process of IK Retargeting, which solved an unrelated issue, and confirmed that the same warnings are appearing when packaging an empty thirdperson template with only a metahuman added.