This tutorial demonstrates a fix for the ‘locked’ hip problem when retargetting animation from the Third Person Character Animation Blueprint to an imported Mixamo character/rig.
In addition it showcases creating a new Blendshape for the Mixamo character using Mixamo imported animations.
https://dev.epicgames.com/community/learning/tutorials/qp52/unreal-engine-mixamo-to-ue5-6-fixing-the-locked-hip-problem-when-retargetting