So, SDHC cards are a little different than regular SD cards (the protocol used to communicate with the card is a little different) and often aren’t supported by particular SD card readers like potentially the SD-to-IDE adapter you’re using.
(I know back in the day, I hacked my Nintendo Wii, which involved loading a bunch of homebrew programs on an SD card, and at first it didn’t support SDHC cards until there was a firmware update.)
Technically, I think any SD card can be SDHC, but almost always SDHC is only used by high-capacity cards. Also, I think they usually say “SDHC” physically on the card.
So, probably the next thing I’d try if I was you was to change out your SDHC card for a non-HC SD card. Any 8GB to 32GB card should be fine, I’d think. (If you have any that are smaller even than that, like 256MB, even, you could at least use it to confirm that’s the issue. You just couldn’t expand the partition sizes out to 2GB.)