Cannot delete empty directory

Hello, I am using a GL-MT1300 to save some videos in a SDcard (with filesystem ext4) , with the purpose of transferred them to a server when I have access to the it, and delete the videos afterwards. My problem is that I also need to delete the directory when there is no videos in it, but I receive this error message:

Command:
rm -f -r “record”

Error:
rm: can’t remove ‘record’: Directory not empty

Also, if I run the command “ls” in the directory, it does not show any files. I tried to format the SDcard, but the error happen again after a while.

If you could give me any hints of what’s going on, I will be happy to hear that

There could be hidden files. Can you try:

ls -la

Someone on the following discussion says it’s a bug when using CIFS:

I