Pipes-to-Ground with the above-ground side facing to the East/right or North/up will not flip when the hotkey is pressed. Ones facing to the West/left or South/down, however, will flip properly.
This is problematic when trying to flip a blueprint, as everything else in the blueprint flips properly EXCEPT the Pipes-to-Ground facing East or North, which must be manually rotated or replaced into the proper orientation afterwards.
Edit: I have also found that when flipping blueprints with a Pipe-to-Ground and at least one other entity, some of the Pipes-to-Ground will incorrectly flip horizontally when the blueprint is flipped vertically, and will flip vertically when the blueprint is flipped horizontally.
