Originally Posted by breni
The strange thing is that I'm able to access the ext SD Card on TWRP Recovery, as you can see on the image attached... I even copied a file (backup.txt) into it.
Sent from my SM-G900F using XDA Free mobile app
Have you tried another SD card in your phone? EDIT: Nevermind this bit
When you plug the SD card into your handset (do it while it's off) Does the SD Storage show anything?
You could try formatting it in another handset if you have the chance then try plugging it in.
Are you using stock Sammy firmware? Or have you installed a custom kernel? Could be one of those playing havoc with your device if so, back up and revert to stock if you can, retest the SD in there.
Test to see if you can retrieve data from the SD card, i've found that although SD cards show up in windows, when I attempt to copy data to the PC it fails, when I say fail I mean it stops progressing and doesn't copy, particular files appear corrupt.
You could also do a chkdsk /f /r via windows on the SD card, or even a general error check.
chances are one of these things will be the culprit, if none and it's still working in another phone and other cards are working in your device then i'm stumped.
Phones: Moto 888 - Nokia 6110 - Nokia 3210 - Nokia 3310 - Nokia 8210 - Samsung e250 - Sony F305 - LG Viewty - G1 - HTC Hero - HTC Desire HD - HTC Sensation - Nokia Lumia 800 - HTC EVO 3D - Samsung i9300 - Asus Prime TF201 silver - HTC One - Galaxy Camera - Z1 - Galaxy S5