Been having issues in the past week with my photos. Take a photo with stock app, it appears in my stock gallery under the camera album, then after varying times the photos come up corrupted (grey box with lightning bolt), sometimes they disappear all together. So I reformatted the SD card the first time via settings, under storage. the card reformats, but then it appears to have data still remaining and yes, I tell it to delete all data. I've reformatted many hard drives in my day and never seen data remain or appear to still be there. In particular, it's the music that seems to be there. also, if I go back to gallery, there are still photos there, and I have my setting set on my camera to save to the external storage. even if I then delete those photos, which are on the camera album, they will re-appear after some time passes. strange.
I've reformatted the card and unmounted and remounted at least 6 times, via the phone and the PC. Nothing seems to get rid of the lingering data. I realize the card must be corrupt?
Using the 64GB microSDXC Memory Card Ultra Class 10 UHS-I
Typically do not touch the SD card until I have an issue.