Editing threads - Bug

Ok, I get this error when I try to cut-copy-paste anything in a thread I'm editing - "Images can be uploaded to postimages.org or imgur.com"

This has never happened before, please fix it!

 Ji-N:

Are you sure it's not an image? That error only pop-up if it's an image.

Nope, I was trying to move text :(  

 Ji-N:

It can't reproduce it, let me know if you run into it again. Help me reproduce the issue.

When I try to move the image to another cell.