2017 i5 21.5 iMac won’t boot to external USB-c
I installed Ventura 13.7.1 on a 1TB Crucial external USB-c drive. When I boot to the internal iMac HDD running Ventura 13.7.1 the USB-c drive is mounted and accessible. When I use the Option key to select the USB-c or select it as the startup drive in System Settings the iMac will revert to the internal HDD each time. Is there a setting I am missing or an incompatibility issue?
iMac 21.5″, macOS 13.7