Originally Posted by stealthpaws
... I changed out the little adapter card case and finally the computer saw there was something...
FWIW, I have fooled around with moving microSD cards between:
(i) a camera (which uses a SD card adapter for the uSD)
(ii) a (POS) USB dongle card reader attached to a computer
(iii) same (POS) USB dongle card reader attached to a Nexus 7 OTG cable (rooted ROM or TWRP recovery running)
(iv) an older Android (Gingerbread) phone
In doing the above, all sorts of bad things have happened:
1) Occasionally the camera reports there is no card present (honestly, I think this is simply loose contacts when using a uSD to SD card adapter). Turning off the camera and re-inserting the card fixes this.
2) Loss of all files necessitating re-format after re-inserting card into Camera following a visit with the N7**
3) VFAT filesystem not recognized by OS kernel on the N7+OTG, but works fine with TWRP with same OTG+card reader (that is, some kind of strange kernel sensitivity)
4) Failure of Camera to recognize media after insertion into the GB Android phone - apparently due to many directories created at the SD card root. Card is not corrupted, but camera no longer recognizes it.
** this would only occur if I used the SD Card slot of the (POS) USB dongle card reader; if I plugged the the uSD card into the uSD slot on the (POD) USB dongle card reader, things were fine. Go figure.
So I guess what I am saying is that - based on my experience - your mileage is probably going to vary .
I was doing all this (albeit not with a Note 3) while I was travelling, and only had the Camera, Nexus 7, OTG cable, camera USB cable, and (POS) USB dongle card reader with me - no laptop or other computer.
Finally what I ended up doing - which seemed to cause the least amount of trouble - was to boot my tablet into recovery, and attach the camera to the tablet as an OTG Mass storage device. That is: the uSD card never leaves the camera
I'm not up to speed about OTG on the Note 3 yet (e.g. is root even needed?), so I don't know what your options are there, but perhaps this gives you a couple of different things to try.
Just make sure you've got all your photos backed up safely off the uSD card before you start experimenting.
I see I am guilty of not reading the OP carefully - you were only moving the card out of the Note3 to investigate what was going wrong, not as a matter of course.
Anyway, it could be a mechanical issue (intermittent contacts), or it could be a bad card. Although card class might make a difference for high-speed writing, you shouldn't experience corruption even if you are using a very slow (class 2) card - unless there are bugs in the kernel.
If you have another card to try out (before you rush out and start buying cards), that might be a useful experiment.