Ha ha! I have found one of the problems. I’ve been looking at your posts on my phone which appears to have cropped off 80% of your images. Now that I can see what you’ve actually posted, things are looking much better!
Try rotating the plane around the horizontal and vertical axes. If the plane is square on to the camera then a tilt lens behaves the same as a normal lens. It’s only when the focus plane isn’t parallel to the image plane that you’ll see the quirkyness of a tilt lens.
J.