I had this working in another place in my app so before I started the work of incorporating AS ViewPagerNative I took another look to see if I could figure out why it worked in one place and not the other.
The code was identical. Checking the layouts in the Visual Designer, I could see that the properties were identical too. Well, if you ignore the margins. Actually, that was the only thing that differed between them. Long story short, if the left margin is set to zero it works fine. If the left margin is 10, the swipe doesn't work. Insane stuff. I tried some more values to see if I could figure out where the breaking point was, and I was getting some inconsistent results.
But then I saw it. The layout with the webview that worked with swipes did NOT use AutoScaleAll. And the layout where the swipe didn't work DID use AutoScaleAll.
So I reset all margin values to their original values and started doing tests with enabling/disabling AutoScaleAll. I can say with absolute certainty that having AutoScaleAll enabled did stop swipe work from right to left (but not the other direction) when using a webview. Clearly something strange is happening there. (It doesn't apply to my case, but I wonder if the people in the threads you linked to did use AutoScaleAll, and if it would have solved their problems.)
All of this was tested by cleaning the project between each run, it was run as debug on a real iPhone.
I've created a small Bug to log this:
This post is to log an unexpected behaviour I found regarding swiping right to left, when a layout contains a webview and the layout uses AutoScaleAll. I can't really tell what level the bug is at, or if it even is a bug in B4i, but hopefully this thread will help somebody else in the future...