grub-probe fails to find the device and asks if /dev is mounted (which it is). This is impeding grub-mkconfig from running properly. Please see https://bugs.archlinux.org/task/18734?getfile=5016 along with the patches there both of which work great for me. Please note that the -9999 version of grub is giving me other issues so I'd like to see it applied to 1.98 if possible. Thanks! Reproducible: Always
Created attachment 262449 [details, diff] Gentooized version of the original patch
Created attachment 262453 [details] Ebuild with the patch
Thanks you saved my day. Here is a simple but cool ebuild and the patch in a more gentooable format.
This issue is fixed in 1.99 and laters.