Debug iOS w/ Xcode results crash on FAsyncNetworkWriteWorker.CheckTime

tested Engine version is 4.18.3/4.18.1, Mac, Xcode 9.2, iOS 11.2.6

downloaded engine source from GitHub(4.18.3) and do essential setup for bring up Editor.
create simple(blank c++) project and generate Xcode project.
opened generated Xcode project and built for iOS device by changing scheme to Debug or DebugGame and changing target to iPhone. And added -filehostip={} arguments for connecting to cook on the fly server.
test project is built and deployed successfully into iPhone.
the black splash screen is appeared, connected to cook server and then started downloading asset - BaseEngine.ini and crashed.

call stack indicated there is problem @ FAsyncNetworkWriteWorker(const TCHAR* InFilename, FArchive* InArchive, FDateTime InServerTimeStamp, IPlatformFile* InInnerPlatformFile, FScopedEvent* InEvent).DoWork().if (CheckTime < ServerTimeStamp) [Line# 990].
CheckTime got 0(zero) and ServerTimeStamp got some value.
moreover, @anonymous_user_0606cc32# 984, it tried to rename BaseEngine.ini.tmp to BaseEngine.ini, but it failed. and the app container has BaseEngine.ini.tmp not ini.
and it crashed during print Logging into LogNetworkPaltformFile category.

i’ve not tested every versions but i’ve debugged 4.16 with no problem by above procedures.

does anybody have any hint for solving this problem?

Thanks in advance,

:frowning: anybody?