After calling ResetDynamics, all the bones reset their settings (eg. Damping, Radius, Stiffness, LimitAngle).

In FAnimNode_KawaiiPhysics::EvaluateSkeletalControl_AnyThread, the ModifyBones array is cleared, if bResetDynamics is true, but UpdatePhysicsSettingsOfModifyBones is not called, unless bUpdatePhysicsSettingsInGame is specified.
I suggest calling UpdatePhysicsSettingsOfModifyBones after the dynamics was reset.