I tried following this tutorial: So my character can look at enemies while its animation plays. I first tried it using a model from mixamo, which worked perfectly. But, I tried using the multi aim constraints on my own character and now it freaks out and floats in the air. Not sure if anyone found a solution but it'd be much appreciated!
If your animation uses root motion or you don't setup your model object correctly then it's going to give you bizarre results. https://docs.unity3d.com/Manual/class-AnimationClip.html
Enabling IK Pass in layer settings (in the animator) and apply root motion in Animator Component fixed this issue for me!
I got this problem too, with a model/rig from blender animated with mixamo, it was due to Armature scale in unity set to 100. In blender during fbx export i set scale dropdown to "unit scale". Armature scale is now 1 in unity and constraint animated model stopped floating or offseting