There is an issue occurring where when updating an animation of a child actor by setting the Child actor class, the animation will flash the skeleton in a T-Pose before continuing with the animation. This issue appears to be a regression
4.18.3 CL - 3832480 - Issue does not occur
4.19.0 CL - 3944462 - Issue occurs
4.20.0 CL - 3952118 - Issue occurs
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-56303 in the post.