I have an intermittent problem with my phone detecting the micro-SD card. Sometimes the phone loses its detection of the SD card and then all storage preferences revert to internal storage. To get the phone to see the SD card again I have to reboot it, sometimes I have to completely remove the card, turn off, turn on, turn off again, re-insert the card and turn on again for it to see it.
The SD card is an Integral 128GB class 10 version formatted as portable storage.
Does anyone else have a problem like this? Did you find a solution?
FYI my phone is a TA-1012 on the latest firmware (July security patch and pro camera update).
A bit of a long shot but do a full format under windows and see if it can be completed, if not then maybe the card is on its way out.
You could also try cleaning the card contacts with a lens cloth or similar soft cloth.