I really like the pattern of using a full page on mobile to replace modals/dropdowns, it utilizes the space much better and avoids a lot of scroll issues… I wonder if adding some kind of x or back button would help? and/or maybe tapping the 
should bring you back to the page before search?
It’s still not very good! We have a lot of hacks to work around iOS scroll issues with modals and dropdowns. As far as I know they don’t consider a lot of their differences bugs at all.