Contrary to advice given here I'm not observing LOST.DIR folder created in cases of corruption. Here's my sequence of steps:
- Unmount external SD card in Android.
- Put it into external card reader for faster file transfer.
- Eject from external card reader. (Using "software eject" of the drive in Windows should which is equivalent to "safely remove hardware".)
- Put SD card back into Android phone and let it "scan media files".
- Directories end up read-only through Android and some files cannot be read because they're reported to be "modified or deleted".
This is sad, transferring files through my phone is very slow which is why I'd like to use my external reader for this.
It appears that Android remembers only the files that were indexed last time and rejects files added externally. Media scanning is suspiciously fast when I insert back the card.