OpenCore - "The bless of the installer disk failed."

I'm currently on a Catalina Hackintosh that was created using Clover ages ago.

I'm wanting to update to OpenCore in the Big Sur transition, but I'm already stuck at the first OpenCore hurdle. I followed the standard OpenCore install guide. Formatted a 32gb USB as MacOs Extended Journaled with a GUID partition map. Acquired the Big Sur installer using gibMacOS. Ran InstallAssistant.pkg, the next step is where the issue arrises. Running "sudo /Applications/Install\ macOS\ Big\ Sur.app/Contents/Resources/createinstallmedia --volume /Volumes/MyVolume", it gets to 100% then 'Making disk bootable... Couldn't extract BaseSystem to path: /Volumes/Install macOS Big Sur/BaseSystem The bless of the installer disk failed.' I tried installing a beta instead of the public release, as well as a new flash drive, all with the same issue.