It's okay. I thought so, but just wanted to make sure before I spouted off a bunch of non-relevant stuff.
Evidently, iOS 8 "messed" up the reading of memory cards and sticks formatted in ExFat (like you can/do for PCs). Evidently, it's HFS formatted memory sticks/cards that can be used on a jail broken iPad.
Here's a link to a conversation (on reddit) that talks bout this issue:
http://www.reddit.com/r/jailbreak/comments/2k7cfe/cckmounting_drives_on_ios_8/
What I get from this is, only HFS-formatted sticks/cards will work ... and then not always.
Not the answer you are looking for, I'm sure. But, it's the only explanation I can find.
Marilyn
P.S. For the heck of it, I stuck an ExFat formatted card into my iPad. The camera roll opened to where I could have imported photos to the iPad. Seemed to be fine. I just couldn't get the card to show up in iFile.
P.P.S. And, since we're talking about a jail broken device, I've taken the liberty of moving this post over to our Hacking section. One, it fits best there and two, someone else with jailnreak experience may have more to add (and they'll see it there).