I haven't tested this myself yet, but my guess is that pinning behavior position updates every tick, while the multiplayer object only sends updates at 30 frames. Normally when using local input prediction and sending client input updates, you would only trigger local movement on client update, which happens at 30fps, rather than every tick, which is what the pin behavior would do at an attempted 60fps.
To resolve, you could try either turning on LAN mode with the set bandwidth profile action (not recommended), or set up control and movement the pinned object manually, like you would the base object.