My folders suddenly turned into 0 byte FILES why? RT-AC87U

Hello cnet!

So I have a 4TB WD Elements Hard Drive connected to my Asus RT-AC87U router. Both the hard drive and the router are new, I just bought them two weeks ago and started backing up my files on to the 4TB drive that is connected to the RT-AC87U front USB 3.0 port.

The copy went fine. But after a day, the folders disappeared. I could not see them from the Windows PC connected to it nor via Android VidOn app that can easily play movies off of Samba/NAS drives.

The ASUS AiCloud app shows the folders as 0 byte files (see image below) and it cant open them.

http://i.imgur.com/hHJscrq.png

When I unplug the HDD and attached to my PC I can see the folders and open the pictures but its painfully slow. ?Moving a 300GB folder within the external hard drive should take a second but takes 15 minutes. Reading the files from the drive is generally slow.

When I run CHKDSK /f on the drive when hooked up to my PC I get an error (I forgot what it was) but it simply gives a one line error and quits. If the drive explorer window is open while doing the chkdsk/f it shuts close as well.

So I am pretty certain this is not the HDD, but the router did something to the drive once it went over certain number of files. I have about 2GB of pictures and movies on it, in file count its probably in the 100,000 count range.

Any help is greatly appreciated!