Hey there, future programmers! After playing with disassembler for a while trying to find the root cause of this old bug I have found that it is probably "autoscroll" logic, clashing with UIPageViewController paging logic. In my case, disabling the autoscroll using aforementioned hack with dataSource = nil is not plausible, since I want exactly what autoscroll offers in drag session. The only solution that I have found is to opt out of UIPageViewController completely and to implement my paging view controller using plain old UIScrollView with isPagingEnabled = true. It is a bit of a complex task to implement dynamic page loading this way, but should not be a roadblock for the experienced developers.