Thanks for the detailed investigation folks. Can I ask that you file this issue in Bugs : ubuntu-desktop-provision
Please include your system specs and the content of /var/log/installer and any crash files from /var/crash which you should be able to find on the 4th partition of the USB key (if you are doing a physical installation). Or drop this information as a reply to an existing bug that covers your issue.
As an experimental feature there is still work to do to expand the FDE functionality for devices that require third party drivers which we are actively working to support within the life of 24.04 LTS.