Hi  mubarakd57262327,We got the same problem on Unique Visitors increase in iOS too,especially on iOS11.Is there any update from Adobe on your issue ticket?Hi Gigazelle​, Since the cases here are all using legacy ID, would wanna know if implement with MCVID can solve the issue or not?Regards,Ricky

Hi there, Thanks for your reply, very useful.May I know more on the logic these default calls? Especially on what conditions would they fire?

Anyone professional can help me?

Hello Adobe Community !I found the following custom link in the report and got some questions:ADBINTERNAL:LifecycleADBINTERNAL:SessionInfoADBINTERNAL:CrashWhat are their functions? Are they necessary? e.g. If we take out ADBINTERNAL:SessionInfo, what would happen?On what conditions would they fire? ...