I have a character animated in Timeline by blending between AnimationClipPlayables. At a given time, the sum weight of two ClipPlayables is 1, and the weight of every other playable in the mixer is 0. But if Clip A keys transforms X, Y, and Z on the character and Clip B keys X and Y only, the status of Z is in limbo. There are a few logical outcomes on Unity's end: Clip B uses the the character's default transform for Z Clip B uses the the animator's state to calculate Z Clip B is pass-through, giving Clip A an effective weight of 1 on Z (normalization approach) Clip B is pass-through, forcing Clip A to blend with (0, 0, 0) because the sum weight affecting Z is < 1 Right now, I'm getting the last behavior — but I want anything except that. Is this the intended behavior? I'm porting an older, state-playing animation library to Timeline and editing every animation clip to have every transform keyed is not ideal.