Install Fail: 'grub-efi-amd64' package failed to install into /target/

Hello all,
While installing LinuxCNC_2.8.2, I keep getting 'grub-efi-amd64' package failed to install into /target/ at the end of installing the ISO image from USB onto a mini PC running an intel celeron N3350 processor.  In the BIOS I have tried and failed with boot mode in UEFI and Legacy, and with Secure Boot disabled. 
I am using the entire disk.  Partition 1 (536.9 MB) is used as an EFI System Partition with bootable flag ON. Partition 2 (61 GB) as EXxt 4 journaling files system with bootable flag OFF.  Partition 3 (1 GB) used a swap area with bootable flag OFF.  GRUB2 is in the ISO, so I don't think I need to add this separately.  It sounds like grub-efi-amd64 is the bootloader.  What would make it fail installation?  Any thoughts?
Thanks!

What utility did you use to create the USB stick ?

For Windows Win32Diskimager (never had single issue with this) is the most reliable as it does a byte by byte copy. Plus it's only a 12.8MB download and works with 64 bit windows.

For Linux dd & USB Image Writer work.

MacOS I believe dd is the go.

This can also happen when there is no internet connection..

Recently win32diskimager let me down and I used rufus instead. Some UEFI vodoo or similar on newer (eg bleeding edge) distros.

That's weird. Did you try dd under Linux ?

What Distro had that issue ?

Was working with Debian 11. Rufus went out and found some stuff on the net and it booted.

In addition to old mates suggestion, boot into a live session and use dd to wipe the partition table.

So it looks like the problem was internet connection?  I say that with a question mark because I was under the impression that the buster.iso was a stand-alone install.  Originally I burned the .iso using Rufus (which I have done successfully on other PC's before), but it kept failing at network configuration.  It kept asking for .ucode files, which I think are the drivers for the specific network hardware on the mini-pc?  Again, not sure.  
So I burned 2.8.2-buster.iso using Win32DiskImager, was then able to connect to the network, and alas able to install the oh so grumpy GRUB, which then led to a successful install.
However, question remain.  I watched vides of linuxcnc being installed with "Do not configure the network at this time" checked.  So when do you need to have an internet connection to install, and when do you not in order to have a successful install?  Or is there a better process?  I took a Celeron N3350 mini-pc that had windows 10 pre-loaded on it, and directly tried to install linuxcnc using the buster.iso.  I did not test the live version because I had previously installed successfully on the same processor on a different mini-pc.  Should I have done something to the machine in the live version first before trying to install?
Cheers! 

I think it's a quirk of the Debian installer. Or maybe the phase of the moon. As for doing something, maybe a magic charm around the PC's neck ?
I dunno it can be a little confusing sometimes. So I really feel for you. If you want to yell at someone, Debian would be the answer.

I had an issue the other day:
The Live version would get an IP fine from my DHCP server (pfSense), when it came to getting one for the installer it would fail on IPv6, so I installed without a network, grub UEFI installed fine (don't ask, I fear it might anger the gods, invite the gremlins in or some other weird thing). When I booted into the installed version, it got a IP from the DHCP server fine.

During all that the installer decided to mount sda1 (first partition on the sdd) and wouldn't let me change the partition table as the disk was mounted. So back to a live session to delete the partition table on the disk.