Just a few thoughts that may (or may not) lead to a conclusion:
-Have you tried another <528MB real hard disk except the one it came with?
-If another hard disk also works but no CF, could it be the CF adapter I'm assuming you're using? Have you tried the same adapter+card on another pc? I read you tried to fdisk the cards on a different machine, but I don't know if you just inserted it in a card reader for example without using the adapter.

If everything else fails, you can always get an easy to build XT-IDE variant such as the ISA CompactFlash which uses only through-hole components. It works beautifully and I managed to assemble 2 of that worked on the first attempt and I'm far from being good at soldering.

I've tried all of those things to no avail. I'm suspecting the issue has to do with the PB PC itself though since I tried the HDD controller in my 8086 machine and although I got a "not a system disk" error with the CF cards It detected and booted just fine from a 120mb and a 420mb IDE hdd that both refused to work in the Packard Bell.

I was wrong about the Prodrive that does work (and is the only HDD I have gotten to work) its a 52MB drive. I don't know whats so special about it that it works and no other drives don't. actually the 120mb drive that failed to work is also a quantum prodrive. I like the XT-IDE cards but
1) I suck at Soldering
2) I'm trying to save myself $60+

OK I see you've tried everything possible, no more obvious suggestions from me...
I understand you're trying to refrain from getting an XT-IDE, but honestly the one with the through-hole components is really easy for anyone to solder. I suck at soldering too 😀 Plus, you can get one pre-assembled and tested right now (just checked). But again you're right and it's respected, it's not for free. It is only an alternative.

(btw, is your exact card model the one with jumpers labeled "E"x? The one where E5 enables/disables support for "old Conner drivers"? If so you could just give this a try too...)

Yes, its the revision with the E jumpers.This is the card.

I have no idea what any of the jumpers do as the only layout guides Ive found like this one http://museum.ttrk.ee/th99/c/S-T/20200.htm are are of different revisions. none of the jumpers are enabled, this is how the card came so I haven't changed anything. I've been told E3 may be the jumper to enable/disable BIOS but the card acts the same if its jumpered or not. Aslo as far as Conner drives, they seem to work in my Epson machine but not the Packard Bell 500.

I've used XT-IDE cards before, actually, I have a spare one but unfortunately there all sitting in a storage unit 2k miles away.

Sorry, not the rev. I had in mind and the only one I am aware of. There doesn't seem to exist any considerable possibility of a faulty card since it's working with 1 HDD, so I rest my case and suggest trying to find some documentation on the jumpers.
About the rev. I had experience with (found it on some site like "total hardware", maybe it was that exact one, I don't remember any more) E5 was documented as something like "enable/disable old conner hard disks support"