While trying to avoid most of the confusing issues (

) it seems the failure to do a proper search is down to the structure of one of the searched HDDs.
So I think that can be put aside for now.
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It appears that the present isolinux is working OK on what it sees as a HDD, but not on an optical drive.
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That being true, then the error location has been narrowed considerably.
I suppose to lock down the above, it would be helpful to see the results of a Hybrid image burned to a partition of a HDD.
If the problem is only with optical media then it should boot in similar fashion to the USB stick.
BTW ..... was the Hybrid on the USB stick on a partition rather than on the full disk?
Maybe it would be useful to ensure it boots OK from both situations ..... if possible to do.
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However, just to add a bit of additional confusion to the full story, I normally boot, and install from, liveHDD images on the 13th partition of the 1 TB drive, and have never seen the truncated loop image search when booting from any of a dozen or more possible boot menu entries from that partition's /grub/menu.lst. For a while, I was even booting from three different hybrid .iso images also stored on that partition.
Were any of the selections booted located on a partition of the same HDD greater than sdb5?
(... or maybe because the initial boot was successful on sdb13(?) the problem was overcome by a different means of accessing the partition ....? )
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So, if any further tests you manage to perform, come out as expected, the failure is down only to the optical drive.
Which would bring me back to this:
This board would not boot to the generic CD-ROM setting, but on further inspection, I found an option to boot from the TSSTcorp CDDVDW SH-222BB device, specifically. It would seem the newer BIOS version is more precise, and therefore more picky, about how code is actually executed.
No DEFAULT or UI Configuration Found
I came across a remark about this error (not UEFI related). It concerned a USB boot ......
It is likely that your BIOS is not looking at the USB drive to boot first. Go into the BIOS and set the boot order so that the USB device will be detected and boot first. There are also legacy USB settings in most BIOS's so that if set inappropriately the system cannot boot from USB. You need to investigate these options before you go any further.
I know you mentioned different boot order etc but cannot find what you wrote while typing this

In some BIOSs there is a delay factor to be edited which might help .... as it seems the optical is not being read for the boot files ..... or I am getting a bit mixed up again .....
Maybe more investigation of the settings in the UEFI/BIOS would suggest more edits to it .....
... getting lost methinks ....