Phone: Samsung Mega
Ext SD: SanDisk Ultra 64GB
Problem 1: Ext SD degraded into read-only. Found SanDisk alert describing this issue as a hardware defect in a specific run of product - weren't I lucky to have gotten two of them! Fixed after SanDisk replaced SD's.
Problem 2: Ext SD only writable by internal apps on the phone. i.e. - Camera can store pix, phone can as well from external source if connected as a media player. However, File Manager, ES File Explorer, etc. cannot write to the SD. Neither can installed apps that need storage space on the SD. Yes, it was formatted by this phone. Yes, I tried both replacement SD's. It seem to me, the SD can be written by the Android OS, but not the user (me), implying we have a security issue. The OS operations done at root and/or SU while apps run as a user.
Thoughts, anybody? Especially that don't involve rooting the phone - I haven't the time or desire to do batl=tle elsewhere.