Thanks for the question!
Unfortunately, as of the writing of this post, these deformer rigs, like the lattice rig, cannot be baked into an animation sequence directly. When you bake control rig animation into an animation sequence, the engine looks at the pose of the skeletal mesh at each frame and simply records numerical values like bone transforms & curve values into an animation sequence and in the end replaces the control rig animation with it. As a result, when the rig goes away after baking, because the deformer is embedded within the rig itself, the deformer goes away with the rig as well. (To be specific, the deformation effect is triggered by the “AddDeformer” node in a deformer rig, feel free to open the rig graph and take a look!)
There is a workaround that with a bit of extra rigging, it is possible to incorporate these custom deformation effects into your character, even during gameplay. Typically a character should have two rigs, one is the animation rig that uses colorful controls to drive bone transforms, used to create animations in sequencer, the other rig is a rig that usually lives in the AnimBp or post process AnimBp of the character, where it handles things like twist bones and corrective joints. This post process rig always runs on the character mesh so if you use the “AddDeformer” node in this post process rig, the deformation effect should stay with the character, even if it is driven by an animation sequence. Furthermore, similar to twist bones and corrective joints, whose movement depend on other primary joints, you might want to also use bones/curves to drive deformer graph variables in your rig graph because only bone transforms & curve values are serialized in the animation sequence.
We understand that this workflow can be tedious and we are actively looking for ways to simplify the whole process. In the meantime, I hope you find this workaround helpful!
Thanks for giving these deformer rigs a try!
Jack