When a user swipes up or down, instead of left or right, the slide content either disappears entirely, or displays content from the next index without actually changing the index.
This only seems to happen on the first or last slide in the collection.
This can only be reproduced on iPhone, and not on Android.
attached video shows the following...
initial horizontal swipe working correctly, forward and back.
then an up-swipe occurs, the slide content changes, but the index does not change. a down-swipe occurs, and the slide content resets.
experimenting further, one could swipe up, see the content change without changing index, and then swipe horizontally, and see the index change, but the wrong content displays again.
It's very bizarre.