Directory of new files - all files lost at nex mount

[KrashDummy]

Using Xubuntu 16.04.

Yesturday I was copying a new folder into a mounted Veracrypt file container (Encrypted file conainer, vfat, Veracrypt). This file copy operation resulted in one new folder and 15 new files within that folder.
It all seems ok, no sign of anything wrong.

Today, I mounted the same Veracrypt volume - and I get shocked to see that every files in the new directory was destroyed!
That means, all the files is 0 bytes in size, and all files have got equal modified timestamp. Possible at the time of dismount or the time of last file saved, or should be saved.

This is a disaster for me, data is lost. I did a backup today - before I discovered that the files was lost, but of course the backup was just the same 0 bytes files too.

The big deal for me now is to know why this happened. What might be the cause of this, and what steps can I take to avoid that to happens?

[KrashDummy]

Hi.

Lucky me had backup so I figured I didn't loose all files. After thinking about this for a moment, I figured there must be one of two reasons why this happened.

1. I used terminal and cp command to copy files to Veracrypt volume. May the cp command have failed to finnish disk writing, despite that on terminal output, it gives the impression that all files was copied?
2. After I unmounted the volume (from desktop, right click --> unmount), I rn the command sudo fsck -M /dev/loop8 on the ext2 file system, and it claimed there was a "dirty bit set". I'm not sure what that is, so I choosed to clear it. There was another message of something (sorry I didn't got a copy from termianl yesturday when I did this) that offered to take backup or reset backup. I choosed to put back the backup that fsck offered.

After some testing, it looks like the volume has no errors no more.

I'm not sure what reason is why that happend. Maybe EXT2 is not an apropriate file system to use in a Veracrypt file container, espechially for small voumes (less than 1 GB).

Anyway - with this incident in mind, I feel that I need to take backup more often. I have another Veracrypt volume on a usb stick that act as backup.
Either that, or I must use a unencrypted folder locally as working folder, and then when I'm finnished, I copy those files to the Veracrypt volume. Only issue is in fact that the most recent files won't be encrypted in case of theft of computer.

Any thaughts ?