[ubuntu] grub rescue "no such device " when selecting grub Windows 10 entry

When I try to boot Windows 10 from grub, I get a grub rescue prompt and:

error: no such device <UUID>
setting partition type to 0x7
press any key to continue

Then a new screen with:
An operating system can't be found. Please remove any disk that doesn't contain an operating system.

I am ruing a dual-boot system (Legacy BIOS, no Secure Boot) with new installs of Win 10 on an SSD (sda) and Ubuntu + NTFS data partitions on an HDD (sdb). I have a /boot partition on the HDD. I can boot Windows fine with BIOS set to boot the SSD. With BIOS set to boot the HDD I get the grub menu with Ubuntu entries (which work fine) and 2 Windows loader entries /sda1 and /sda2 (which both result in the error).

This is *after* I ran boot-repair in Ubuntu with the "recommended" option and installed grub to sdb. Before that grub didn't show the /sda2 loader. I don't want to try any more "fixes" at this point without some advice, since I'm not sure what the failed boot-repair did.

My current bootinfo output is at http://paste.ubuntu.com/15290020. The UUIDs I get in the grub rescue error messages match the blkid output for the selected loader entry.

Device UUID TYPE LABEL
/dev/sda1 94109C4D109C3866 ntfs System Reserved
/dev/sda2 CE4E9DD04E9DB227 ntfs

Also, the boot flag is on my / partition (sdb6) not my /boot partition (sdb7).

/dev/sdb6 * 2,929,704,960 2,968,764,415 39,059,456 83 Linux
/dev/sdb7 2,968,766,464 2,969,741,311 974,848 83 Linux

Thanks for any help...
-LloydM999

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