This report is very similar to UE-50805 (the command line used to run the build is slightly different), but the build fails with a different error. In this case, a source file is being looked for, but it appears that the build may be trying to use a path from the remote Mac to look for the file on the Windows machine. Log file is attached.
Attempted to reproduce on Master (Main), but that failed with a different error (log file also attached).
Make sure the Engine is set up to remote build on Mac. This can be done by opening the BaseEngine.ini file and setting the RemoteServerName and RSyncUsername values in the [/Script/IOSRuntimeSettings.IOSRuntimeSettings] section to connect to the remote Mac. Ensure that a valid remote build SSH key is applied for the Engine, and that Mac platform files are included in the Engine (run Setup.bat --include=Mac).
Run the following commandline to create a local binary build of the Engine: Path\To\RunUAT.bat BuildGraph -target="Make Installed Build Win64" -script="Engine\Build\InstalledEngineBuild.xml" -verbose -set:WithIOS=true -set:WithWin32=false -set:WithMac=false -set:WithAndroid=false -set:WithTVOS=false -set:WithLinux=false -set:WithHTML5=false -set:WithPS4=false -set:WithXboxOne=false -set:WithLumin=false -set:WithDDC=false -set:WithFullDebugInfo=false
The build fails on the final step (Make Installed Build Win64) with the error: ERROR: Source file 'D:\Users\compile\UE4\Builds\RDU-WD-8498\D\UnrealEngine-4.20.3-release\Engine\Intermediate\Build\IOS\UE4\Development\Launch\Module.Launch.cpp.o' is not under 'D:\UnrealEngine-4.20.3-release'
The build completes successfully.
There's no existing public thread on this issue, so head over toAnswerHub just mention UE-64493 in the post.