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First time poster here.
After installing High Sierra on my iMac (27", late 2012) my Boot Camp Windows 10 partition is no longer visible in the Startup Manager (accessed by holding Option-key on startup).
When logged into Mac OS, I can see the bootcamp-disk, and it's also visible in Startup Disk. Edit: it's visible in Finder, hence a different problem than described in other questions.
Edit: When I try to boot to Win from Startup Disk, the computer froze on first attempt. On second attempt, it displayed "no bootable device - insert disk and press any key".
I run OS X 10.13.2. Any help is greatly appreciated, thanks in advance! /Johan
Edit: the disk is a "fusion drive".
Edit: As a (at least temporary) solution, would it be possible to roll back the system using Time Machine, to before the High Sierra uppgrade?
Edit: I solved the issue by simply removing the bootcamp partition, starting from scratch with a new Win 10 installation. However, the Win installation failed several times. The installer wouldn't accept the bootcamp partition. After some googling I did a PRAM-reset, which did the trick. I don't know if this was caused by my original problem with the missing partition.
Thanks for the replies and suggestions, guys!