Figured out why this happened: it's impossible to pinch with an index controller (at least, I haven't been able to figure out how). The pinch function also clicks the cursor in the interface. I bound pinch to analog stick - south, and that fixed the issue for me. If it would be possible to make it so pinching isn't required to interact with the dialog, that would be less anti-intuitive. I think I'll re-bind pinch to the trigger, now that I know what pinch is responsible for.