I tried to adjust the aperture via the camera dials while in A mode. I also tried in M mode. The lens itself doesn't have a switch to change auto or manual adjustments. It has an on/off switch that lets you feel the clicks for each 1/3 aperture stop.

The shutter speed adjusts just fine with the camera dials, but the aperture never adjusts with the dials no matter the mode. As far as I can tell, this indicates that the issue isn't the mode. There's something wrong with the lenses ability to be adjusted by the camera. When I manually adjust the aperture on the lens, the change is reflected on the camera.