If I hold option while booting, then I momentarily see a folder with a question-mark icon for a fraction of a second followed by the normal apple icon and then booting into the primary drive. I do not see Startup Manager or any kind of prompt to select a drive.
It doesn't make any difference whether no drive is connected, the USB 3.0 drive is connected, or even an older USB 2.0 drive (which is bootable) is connected. I tried all three combinations, and holding down Option behaves as described above regardless.
However if I use System Preferences > Startup Disk I can still boot into the USB 2.0 drive (but not the USB 3.0 drive).
|