Properties that uses DOREPLIFETIME_ACTIVE_OVERRIDE (ex. RepRootMotion ) will also skip replication when an actor channel is newly opened.
This means that if the variables on the server side do not change, the opportunity to synchronize the property will be lost forever.
ACharacter::RepRootMotion.IsActive on a client will be fixed to a false value due to this behavior, and it disables root motion movement synchronization.
The following workarounds works. It will check the properties when the actor channel is newly opened regardless of the DOREPLIFETIME_ACTIVE_OVERRIDE flag.
There's no existing public thread on this issue, so head over to AnswerHub just mention UE-119442 in the post.