Question: Option Startup not working since upgrading to High Sierra
I have a 2017 iMac with an internal SSD. I have Bootcamp Windows 10 on an external USB 3 SSD. On OS X Sierra, I would Option-Startup and select the EFI drive and boot into Windows 10. I just upgraded the iMac to High Sierra and Option-Startup no longer works. No boot drive selection is displayed.