In the LF world, lenses do not have a flange distance like those on the DSLR world: in a DSLR camera, the lens stays at a fixed distance from the sensor, and the focusing is performed by moving one or more optical elements inside the camera; in a LF camera, the whole lens is moved back and forth. Now, simplifying everything a bit, and assuming that your Schneider Digitar lens behaves like an "ideal lens", we can use the following formula:
1/D = 1/d + 1/f
where D is the distance from the lens to the focal plane, d is the distance from the lens to the focused subject, and f is the focal length. Thus, a 35mm lens is expected to focus at infinity when placed at 35mm from the sensor, or closer to focus on closer distances; and coincidentally this matches what you have already found.
Now, the problem when attaching a DSLR camera to a LF lens using bellows, is that the front of your camera is where the LF film is expected to be. But the sensor is some millimeters behind, so the lens should be moved behind too, and sometimes it should even have to enter the camera to be able to focus on infinity.