That's interesting that HII 'changed' between 9.5 and 9.6 because we didn't make any changes to the discovery, download or processing of drivers in WinPE. From a code standpoint it should be identical to how it was before.
If you can get the HIIClient.log file from the client machine that would help a lot. It should be in the X:\ldprovision folder while in WinPE and it gets copied to the C:\Windows\Temp directory so you can see the results after leaving WinPE. Either copy of the log would be fine.
Thanks!