Old Windows 10 Machine - Cannot execute reagentc /enable after MBR2GPT migration because script cannot update boot configuration data

Question

After updating migrating my Windows 10's disk 0 from MBR to GPT using the MBR2GPT tool, I found that I could not enable the Windows Recovery Environment using reagentc /enable in an elevated command prompt.

Remarks:

1. The system is running on a Lenovo ThinkCentre M92P that was updated from Windows 7 Pro (the original OS) to Windows 10 Pro. This update happened when disk 0 was still in MBR mode.
2. The BIOS supports both Legacy and UEFI mode.
3. bcdedit cannot find the BCD file unless it is directly specified using the /store flag, regardless of whether the full OS or Windows PE mode is running.
4. I have a Windows 10 installation CD that I can use to run the Windows PE command prompt.
5. Unlike some other users who have experienced this problem, I am able to run Windows. I just can't access the Windows RE menu items when holding "Shift". The only item available in the "Troubleshoot" menu is "UEFI Firmware settings."
6. Because MBR2GPT was used, the partitions aren't standard: the recovery partition (System_DRV) comes first, followed by the EFI partition and the C drive. There is no MSR partition.
7. I have another Lenovo ThinkCentre (we'll call this PC 2) that was also updated from Windows 7 to 10, and migrated from MBR to GPT successfully. reagentc was enabled without a hitch, so I'm not sure what is going on with PC 1.
8. The computer used to be a dual-boot Windows-Linux machine, with the Linux partition stored on another disk (Disk 1). However, bcdboot was used to reset the BCD configuration file.
9. Windows RE worked before the MBR to GPT migration.

Things that have been tried:

9. I've ran the following in an elevated terminal, but reagentc still cannot enable Windows RE successfully. sfc /scannow
   DISM /Online /Cleanup-Image /RestoreHealth
10. In Windows PE mode (where the C drive is called "D"), I've used diskpart to assign V: to the EFI partition and ran
    bcdboot D:\Windows /l en-US /s V: /f ALL
    successfully.
11. Use the Windows 10 CDto boot into Windows PE, then execute "Startup Repair," which fails.
12. Run Windows normally, then "run" the Windows 10 installation disk. This is to see if I can reinstall Windows, while keeping my files. I get a "Sorry, we’re having trouble determining if your PC can run Windows 10" error.
13. In Windows PE, run reagentc /enable /osguid {GUID of the default bootloader}. I get a "REAGENTC. EXE: Unable to update Boot Configuration Data. Access denied." message. The "Access denied" error does not appear when running reagentc in the full OS.

Screenshots/Logs

Reagentc logs: https://controlc.com/7f8fafdd
Diskpart logs: https://controlc.com/8269a89c
BCDEdit logs: https://controlc.com/bb43b2c6
System_drv dir logs (showing that the F drive contains winre.wim): https://controlc.com/207edf59