I discovered today that after landing on another user's mpcarrier in GIT, the plane does not sync to the deck if the ship is underway. Instead, it's stationary relative to the ocean, and the carrier steams out from under it. Ditto even after the holdback is engaged. This occurred with several of Dave Culp's JSBsim models that work fine in 2.0.
More humorously, the PBY thinks the carrier deck is water, and sinks up to the plane's waterline when landing. Even throws a roostertail.