omg, so fixed position doesn't work in ion-content, which uses zynda scroller... see here
"The ion-scroller is based on the zynga scroller, which really just movies content inside the scroller. Technically, it's not scrolling, but just moving the content inside. "
the workaround is set and then set {'scroll:overflow; height:95%'} to the content you want to scroll inside of it