DPReview member, skutters, had difficulty discovering how to use aperture priority with his XF zoom lenses. He had no problem using it with his primes. Had Fujifilm labelled the aperture rings of their variable aperture lenses (as had been done for decades by various manufacturers), not to mention install aperture lenses on every lens, such confusion wouldn't ensue.
The good news is that skutters figured it out. The bad news is that Fujifilm are removing labels and stops even from their fixed aperture zooms.
DPReview: Can not select Aperture with my new XE2 and zoom lenses