Should not be hfs. The fact it formats means it's probably fine. The issue lies in the Mac most likely.

Has the CC been recapped as my last CC seemed to "brick" hard drives before I had it done. When not recapped or has iffy traces it can be very temperamental if anything works at all. I used had disk toolkit when i use third party drives. It's usually pretty easy to get a hold of.

Another thing to check is the card itself in the slot. The fact it's smaller than the hard drive and weight on the flimsy slide in connection when the whole computer is at an angle inside already may make it flaky also. Also bent pins along the while chassis plug inside. One pin can cause a bunch of havok.