Hi guys,
I've got a similar, but not identical, issue on two of my Samsung devices (Note 2 and Tab2 7.0). I purchased two Sandisk Ultra 64gb class 10 microsd cards. Both are recognized by the devices, but when I try to create a folder or copy a file I get an "Access denied" message.
When I remove the card and use a reader and attach it as USB Mass Storage, the card works fine. I can't try it in another phone, like my Evo, because their limit is 32gb. Since it works as mass storage but not as an extSdCard, it doesn't sound like the card is the issue. Perhaps the way the device's microsd card reader is configured?? Oh, yes, the card does work fine in my Note 10.1! More evidence that it is the devices and not the card??
At any rate, I've tried everything I can think of to fix the problem without success; formatting in each of the devices, formatting as mass storage via USB, formatting with a highly rated utility from the play store. I even tried the "Protect SD card" as suggested near the beginning of this thread. Nothing I've tried has worked. So, what do I do, besides complaining to Samsung, which sounds like they are in "Access denied" (denial) mode? (Sorry for that last convoluted sentence).