Use the ISO which was successful in resolving the update issue. That one most certainly has the September patch included in it. If it doesn't end up working on your new machine, you can simply run the setup.exe and tell it to check for updates before installation (it will be just an in place upgrade, so no data or apps will be wiped).
Edit: If nothing works, just don't install any CUs. The 20H2 update is right around the corner and will soon be publicly available. Upgrade to 20H2 directly and it should install without any issues.