I do recall, that I had some trouble with writing a new boot sector to some of the CF cards I had created for the D8B and HDR.
I don't recall the details how I solved it, but remember that I had to take some pretty strong measures with at least one of them, to not just add a partition within a patition within a partition every time I tried to overwrite it with a new boot sector, but actually have it blow all those previous attempts away and format the card completely - including the boot sector on the CF card.
This is kind of a topic in itself, and I'm not sure if I fully understand it. But you might want to google something like
"cf card overwrite boot sector"
The AI overview I got when searching for this, pretty much recommended not to overwrite the boot sector on CF cards, since this could damange them and make them unusable... but this is DEFINITELY necessary for the Mackie OS to be able to boot from CF cards.
So, you'll need to find a way to fully erase those CF cards (or better find a way to restore a disk image that doesn't just write another boot sector next to the original boot sector, but actually replaces it).
I honestly don't remember what I did to get CF cards to work again that acted up... it might have been some command-line low level format via Linux (...when I'm stuck with Mac or Windows options, I usually try via Linux... it's not as restricted and lets you do a lot more "unsafe" things, like writing a boot sector that could "damage" something, haha).
In other words, I'd have to research this whole thing from scratch again myself, since it's been years since I had to do a sort of "brute force" CF card "full format incl. boot sector".
Most of the time I did this sort of thing, it just worked... it was just these couple of rare times, where I had to jump through a whole bunch of hoops to get a CF card working again.
...and I did kill one of them that I couldn't get back... but that just died during use, not when I tried to format it or something.
I'd recommend to do a little bit of your own research for caveats of trying to write a new boot sector to a CF card... I can try to help again when you also read up on it a bit (or try to clarify cryptic explanations you might find online)... but think that this was such an oddball thing to get working, so that I think it would be better to not just rely on the little bits I might be able to piece together if thinking really hard how I had solved this, but also try to read up on it "in general" a bit, first.
So, yeah... writing a new boot sector to a CF card, or even FULLY erasing it and writing brand new partitions, is not really what CF cards were designed for, I think. But it DOES work, when it's being done right... so, don't give up just yet
Best of luck in the meantime... but I'm happy to pick this back up... just don't have any specific recommendations for this readily available, sorry!