Why is that?

I get the sense I've been had by script-kiddies.

The official ASUS 1805 BIOS gave me a nice, full-screen display when I entered the UEFI BIOS.

NOW, with the UBU "modified" (or is that "hacked"?) version, I'm looking at a frame in the middle of my display.

So?

ETA >> I am SERIOUSLY unimpressed with this Micky-Mouse bullshit.

I'm going to flash back to a PROPER Asus BIOS.

You have updated your vBIOS and/or GopDriver to the version without setups needed for your board, that is why you see this resolution change. Don't touch both of them and it will be fine.
Any modification can break anything, if you are afraid of it, just use PROPER BIOSes.

I had have a similar problem that no one was able to solve it seemed like, i searched the internet as why my Intel Graphics showed my BIOS in full screen but my NVIDIA card did not it had black borders and text looked bad.

I knew a thing or two about some BIOS settings and said let me try to change the CSM settings cause it only had UEFI set on one thing and that was the boot drive.
Well there's an automatic option in my ASUS Z97-K BIOS for CSM to be put on automatic that will figure out what each setting needs to be in there depending on my hardware, a UEFI BIOS on the GPU or a legacy.

Once i put CSM to "Auto" i saved and exited and then my bios was in fullscreen, and it made sense to me and that's why i thought to look in their and change some settings cause it loads the driver for the hardware.
If it's set to load Legacy driver on a GPU with a UEFI BIOS on it then it makes sense why it wouldn't work, vise versa too.

So go into your CSM settings on the Modded bios and try to put it on auto if this doesn't work try changing to manual and go to the PCI-E part of the settings and manually select UEFI and Legacy or just UEFI and see if it works.
In your case it could be something with the Option ROM but this may help as it helped me, and i could not find anywhere on the internet telling me to do this to solve it, everyone just said upgrade to a 700 series nvidia card to fix it and its the BIOS on the card's fault which also makes sense but i found a fix that's 100%.

OP, what a nice way to return something to the user who donated his time and knowledge to help others. I'm sure Sonix is thrilled by such feedback, please continue with your excellent reports. Who needs educated users who know a thing or two before doing BIOS modding, who needs users who are willing to help isolate the problem (to be honest, I think the problem isolated itself from the beginning)?

UBU has plenty of satisfied users, only now and then comes a hit-and-go report about mystical and dangerous powers hidden inside a .bat file. Every software has its trolls.

On top of the display issue, I get a sense of déjà vu with this BIOS - changes in settings are being ignored by hardware.

For the hell of it, over the last couple of days, I thought I'd see if I could OC my i5 2500K to 4.4GHz stable, without any voltage increases (from the 4.2GHz it's run at since I built the PC).

I've always used a -ve CPU vcore offset of -0.01v, which gives 0.986V idle (1600MHz CPU) and 1.298V in stress tests (4200MHz) with Load Line Calibration (LLC) at medium.

The 44x multiplier simply ***will not stick*** with this hacked BIOS, no matter what.

Instead, what I've had to do is up the BCLK to 102MHz (with a 43x multiplier), which gives me CPU clock of 4396MHz and slightly over-clocked RAM (c. 1632MHz).

Whatever is going on, UBU seems to be doing more to the code of the Asus 1805 BIOS than just changing the RAID OROM.

Put simply, this UBU hacked BIOS is flakey as f***, no two ways about about it.

Can you consider banning that ungrateful POS?