I had a problem with Network Printer migration. I tried few times and every try was not successful.
USMT Logs examinations show the following message:
"Downlevel Manifests Folder is not present. System component settings will not be gathered."
As you can see from the picture ScanState.exe has been started from UNC path
ex: \\server name\share name\usmt\x86\scanstate.exe c:\DataMig /i:\\server name\share name\usmt\x86\\migapp.xml /i:\\server name\share name\usmt\x86\\miguser.xml
To resolve this issue my testing showed that Scanstate.exe should be executed directly in USMT working folder:
ex: scanstate.exe c:\DataMig /i:migapp.xml /i:miguser.xml
net use x: \\server name\share name\usmt\x86\
x:\scanstate.exe c:\DataMig /i:migapp.xml /i:miguser.xml
Using this way USMT Scanstate.exe will find a path to the appropriate manifest folders.