Tony, just another option. Try a windows computer. A little off subject but.....
Several years ago I purchased several very inexpensive CF cards. They worked in camera but would not read on my windows computer. I have one of those HP printers with all the card slots. Stuck it in there and was able to read and download the images. Card never did work straight into the computer, but was always readable via the printer. Never could understand why.
Good luck.
So if the card comes back from Transcend as "not their problem". I'd recommend finding one of you computer friends who has multiple computers with multiple OSs, like I do. And see if there are any OSs that will mount your card. Generally a version of Linux will do this very well because they will be able to do everything manually. If something doesn't work on a mac after a couple tries it is rare that you'll be able to get it to work.
I have a Sandisk Firewire CF card reader if you want to try something different. Not sure why it should make a difference but you never know. You can give me a call as I am just down the street at 1409.
Edit, See I am a bit late now that you have sent the card to Taiwan, good luck.
We regret to inform you that Transcend has finished the data recovery process on your device, but no data could be recovered. Unfortunately the tools and techniques that were implemented for the recovery of your data were unsuccessful. We are sorry that we were unable to assist you with data recovery of your files.
So, did they send you back your original card in the same state you sent it?
If they did I think you can do a quick format using DiskUtility (so it will mount) and then run a data recovery app which recovers files from a (quick) formatted drive. The files names will all be wrong but it should recover all of the images. I haven't tried this on a CF card or any other SSD but I have on FDDs and HDDs with perfect success.
Unless there is something actually broken about your card I have to conclude that the guys there at Transcend are nincompoops!
You can conclude all you want, but I would think their techs in Taiwan are more competent at recovering data from their own cards than others are.
You are making an assumption that the data is recoverable. That is not always the case. As for Disk Utility, that was useless as the card would NOT mount.
Ah, yeah, then the only thing even possible at that point would've been to desolder and transplant the chip into a working card. Might be worth it in some cases... Not sure about yours.
Anyway, sorry to hear you lost all those images. Bummer!