Windows Boot Manager can't boot grubx64.efi

I tried adding grubx64.efi in the Windows Boot Manager using BCDEdit. However when I boot up my computer and try to start GRUB from Windows Boot Manager by clicking on the entry I created, I get:

File: \EFI\ubuntu\grubx64.efi

Status: 0xc000007b

Info: The application or operating system couldn't be loaded because a required file is missing or contains errors.

I know that the efi file works because I can boot GRUB up, from the same file, from the same location (the ESP partition) using an EFI shell, such as the one found in this answer: https://unix.stackexchange.com/a/63898/167564

Here's my bcdedit output:

Windows Boot Manager
--------------------
identifier              {bootmgr}
device                  partition=\Device\HarddiskVolume2
path                    \EFI\Microsoft\Boot\bootmgfw.efi
description             Windows Boot Manager
locale                  en-US
inherit                 {globalsettings}
flightsigning           Yes
default                 {current}
resumeobject            {4c60dca4-e732-11e5-be25-b3798e2bd780}
displayorder            {current}
                        {4c60dcaf-e732-11e5-be25-b3798e2bd780}
toolsdisplayorder       {memdiag}
timeout                 10

Windows Boot Loader
-------------------
identifier              {current}
device                  partition=C:
path                    \WINDOWS\system32\winload.efi
description             Windows 10
locale                  en-US
inherit                 {bootloadersettings}
recoverysequence        {4c60dca6-e732-11e5-be25-b3798e2bd780}
recoveryenabled         Yes
isolatedcontext         Yes
flightsigning           Yes
allowedinmemorysettings 0x15000075
osdevice                partition=C:
systemroot              \WINDOWS
resumeobject            {4c60dca4-e732-11e5-be25-b3798e2bd780}
nx                      OptIn
bootmenupolicy          Standard

Real-mode Boot Sector
---------------------
identifier              {4c60dcaf-e732-11e5-be25-b3798e2bd780}
device                  partition=\Device\HarddiskVolume2
path                    \EFI\ubuntu\grubx64.efi
description             Grub Test
locale                  en-US
inherit                 {globalsettings}
flightsigning           Yes
custom:23000003         {current}
custom:23000006         {4c60dca4-e732-11e5-be25-b3798e2bd780}
custom:24000001         {current}
                        {4c60dca8-e732-11e5-be25-b3798e2bd780}
custom:24000010         {memdiag}
custom:25000004         10

As you can see by the output, the last entry was the one I experimented trying to get Grub to work, the one that says "Real-mode Boot Sector". I created it by creating a copy of "{bootmgr}", and renaming it to "Grub Test", and changing the path to where grub was located. I saw this answer, and it says the correct entry is bootsector, so I went into regedit and changed it from "Windows Boot Manager" to "Real-mode Boot Sector", by changing values under BCD00000000 as explained in this post: Windows 8.1 UEFI x64 is not able to boot-up UEFI Images

I also tried changing it to:

• 0x10100003 (Firmware Application)
• 0x10100002 (Windows Boot Manager)
• 0x10200003 (Windows Boot Loader)
• 0x10400008 (Real-mode Boot Sector)
• 0x20200008 (Inherited Settings)

However they all ended up with:

File: \EFI\ubuntu\grubx64.efi

Status: 0xc000007b

Info: The application or operating system couldn't be loaded because a required file is missing or contains errors.

Can I somehow make Windows Boot Manager be able to boot Grub? I searched all over the Internet and couldn't find anything of use to me, I'm kind of frustrated.

Also, secure boot is turned off.