Dialog Box (Message,Confirm) in IOS with Nav Web Client 2015

I have a problem when I open pages that have any dialog box (i.e messsage or confirm) on Web Client in IOS (iPad o iPhone). The dialog box doesn't appears so that the main page is blocked and I need to re-start the sesion. I don't use Nav web App and I work with Safari browser. I have unblock pop-pups but I can´t see dialog boxes. If I open these pages on Windows or Android, I can see all dialog boxes and it works without any problem.