Backups grayed out in Migration Assistant

My MacBook 12" 2017 running Ventura 13.6.6 was malfunctioning so I decided to reformat the hard drive and reinstall. Migration Assistant sees my external backup drive. However, the backup is grayed out and the continue button is too.

If I start the machine and open with Finder the external drive, the backups are there.

If I try to use Time Machine it refuses to select the drive because it is not empty and offers to erase it. It is formatted APFS case-sensitive.

If I reboot with cmd+R and try Time Machine System Restore all backups are visible but when I click continue I'm told to reinstall OS and use Migration Assistant, which is what I was doing.

Thanks