OK, here's a few things about the commands you are running.
1 - /uncpath will go to the core server and get the HII repository path directly from there. There is no need to supply the path. Even if you do it is ignored and whatever is configured from the core is used.
2 - In non-preview mode the os and arch parameters are also ignored. We will gather drivers based on whatever OS is on the hard disk, so those are redundant.
So, go to WinPE and run hiiclient.exe /uncpath. That should create an HII log file in the \Windows\Temp directory on the client hard drive (not the WinPE RAMDisk). Attach that log file and let's see what we find. If that doesn't give us everything then we'll ask for a copy of your drivers db3 file and a log file from running /previewAll to see what we're up against.
Thanks!