Can't boot M1 Mini (Sonoma) from external drive.

I set security on the Mini to allow startup from external media. I formatted a new 2tb SSD per instructions and installed Sonoma. All went well until the installer tells me to restart, but it restarts from the Mini's internal drive. When I tried to set the new drive as the startup i get an error message "this volume cannot be used since it has a secure token without any users." How can I set up the new system if there is no way to restart from the new drive?"