I\'ve been experiencing an issue in mobile versions of webkit (specifically Webkit 534.46 on iOS 5.1.1 as mobile Safari, and now Chrome for iOS) which doesn\'t happen on any
My install of iWebInspector is pretty busted right now, but after messing around with jsfiddle and the iOS sim it seems like your hunch is correct - despite being position:fixed, the browser thinks the page has scrolled, and screws up the click targets.
It looks a lot like this is the same issue as iOS Safari: Anchors within a fixed positioned element only work once, which also hasn't been solved with pure CSS. Also related: Fixed position navbar only clickable once in Mobile Safari on iOS5.
Tangentially, and I'm sure it's been noticed already, it's not possible to scroll the left side, so on an iPhone the index only shows A-M.