I was playing with my new VGC team on Showdown when I encountered something odd. I had my Aegislash and Lopunny vs. Mega Charizard Y and Bisharp. I predicted a Heat Wave and used Wide Guard, knowing that I could either survive a Knock Off or waste a Sucker Punch in Shield Form. However, when I used Wide Guard my Aegislash did not revert to Shield Form. I could have sworn it had happened in a live VGC match in XY, and since Aegis changes forms when using a defensive move (Protect, King's Shield), it stands to reason that Wide Guard should force a change. In the end I blocked Heat Wave and took a Knock Off full to the face of my paper-thin Blade Form.
Is this a unsettling Showdown error, or am I mistaken in believing that Wide Guard makes Aegislash changes forms with Wide Guard?