How could you be caught out?
Because I’m grossly incompetent. It had nothing to do with being led into error by the counter-intuitive functioning of the different charts in the same EFB. A VTC doesn’t zoom to its own inset. Go figure. I now just use the mega map that includes the insets. Swapping from an individual inset to an individual VTC then to a VNC and vice versa in a busy arrival or departure environment is unnecessarily distracting.
I’m just trying to help others understand the issue to hopefully reduce the possibility of others making the same mistake.
It must be very satisfying being perfect, Bloggs.