We have tagged and released v0.8.3 of the Asahi Installer, which includes a fix to make Asahi installations visible to the macOS 27 boot picker and Startup Disk applications. If you installed the macOS 27 beta and have been affected, please re-run the installer from macOS. There is a new option that will set a bootable flag in the Asahi APFS volume's metadata, making it compatible with macOS 27. All new installs will have this flag set automatically going forward.
We are still discussing a solution for existing installs to avoid requiring everyone to run commands manually. It is possible to apply the required fix by running commands from Linux/*BSD, however this is not our preferred solution.
In addition to this bug, macOS 27 also introduces changes to the SMC's firmware interface for battery status information. These changes confuse our driver, which may trigger unexpected emergency shutdowns. A fix for this has been developed but has not yet been released.
Our advice remains to avoid the macOS 27 developer beta, and developer betas more generally. It is unlikely that they are tested on machines with third-party OSes installed on them, and are not suitable for production systems.