Sure, the cookies expire (in two weeks I think, in this case) but that doesn't invalidate the issue that the wkwebview silently shares cookies with nsurlsession, nor does it negate the confusing journey of tracking down the bug. Sheesh.
I'd be surprised if AFNetworking didn't also offer the ability to create a "private" NSURLSession with custom storage objects.
I'd also recommend looking into debugging these types of issues using, eg, Charles Proxy. There's more information on logging at:
https://developer.apple.com/library/content/qa/qa1887/_index...
See also:
https://developer.apple.com/videos/play/wwdc2013/705/
Disclaimer: NSURLSession contributor...