Creator's upgrade appeared ok, but Advanced Recovery functions fail

Some progress- and some things learnt.
reagentc /enable wouldn't work at all as shown above. I have succeeded in getting that to work.

Recall my 'build' was a clean install (when all worked) with 'C:' replaced with my current system partition. Having done that, I had no Advanced recovery options.

Having 'fixed' reagentc /enable, I now have those back.

reagentc /info now gives what it should:
C:\windows\system32>reagentc /info
Windows Recovery Environment (Windows RE) and system reset configuration
Information:

Windows RE status: Enabled
Windows RE location: \\?\GLOBALROOT\device\harddisk1\partition1\Recovery\WindowsRE
Boot Configuration Data (BCD) identifier: ea28bca3-a098-11e7-8bcb-a434d962e85a
Recovery image location:
Recovery image index: 0
Custom image location:
Custom image index: 0

REAGENTC.EXE: Operation Successful.

How? Two things.
To get reagentc /enable to work:

1. Copy winre.wim to C:\Recovery\WindowsRE
2. Following

[SOLVED] How Do I Prepare Windows Recovery Environment on Windows 10. Taking Backup Measures on Your Windows Using ReagentC Tool and PowerShell


zero entries in
C:\Windows\System32\Recovery\reagent.xml

It may be necessary to create winre.wim using the appropriate Win 10 install iso; if the iso contains install.esd, this needs to be converted to install.wim using the appropriate DISM command.

Then run
reagentc /enable


Alas - I'm now back in the same state I was in quite some time back, where attempting to use the boot to Safe Mode option => just a PC logo, nothing more, and booting to a command prompt takes me to a PC logo with Please Wait at the bottom of the screen.

I.e. I have all the Advanced Recovery Options - but they don't work.

Solved! by an unexpected means...

Recall I had upgraded from the AU to the CU and could not boot e.g. to Safe Mode - on restarting to try to do so just the PC logo, no activity.

This time I started by wiping all Windows partitions, then clean installing the CU, intending should all be well to restore my system partition from my Macrium partition image.

I noted that trying to boot to Safe Mode via SHIFT + left click restart -> error 0xc0000454 - The boot configuration data for your PC is missing or contains errors. Shock, horror, jaw drops etc...

Curiously, selecting Safe mode via msconfig worked.

I tried again, and noticed this time when deleting partitions using the Win 10 installation sequence, that the disk numbers for my two disks (SSD, SSHD) were reversed compared to when shown by the partition manager. Thus now the SSD was shown as Disk 1. I deleted the partitions. During the installation process I also noted on the restarts there were a couple of short lines briefly shown on a black screen indicating no boot source had been found (not the exact text- it was brief and obscure).

Now I hadn't been used to seeing that.

Restart to safe mode again => 0xc0000454.

======================================
Time to reinstall 1607 - the AU- which had worked.

This time the disk numbers were 0 for the SSD, 1 for the SSHD.
I deleted the Windows partitions on Disk 0, reinstalled. During the reinstallation process there was no message on restarting during the process.

I tested restart to Safe Mode- fine.

I then restored the image of the CU Windows partition and rebooted. All is now well.

Now, that begs at least the following questions.
a. Had I upgraded to the CU with only my SSD in, or clean installed it thus, would all have been well.
b. What is the significance of the disk number reversal between the AU and the CU?
c. Given I now have my recovery, system, EFI partitions created from the 1607 build and my Windows partition from the CU build, and all seems well- is there any discrepancy that is likely to catch me out?

(Note: when I first rebooted this concoction, it (unsurprisingly) did an automatic repair- which succeeded).

Has anyone else noted their system disk not being designated as Disk 0 by a CU build on installation?