Hi Igor,
I encounter the exact same problem. Unfortunately it doesn't disappear when I wait (5-10min). I am using a new Sandisk 8GB SD Card for my Cubietruck. I tried the Vanilla Jessy and Vanilla Xenial Images. I copied them to my SD Card once with Rufus and once with Win32ImageWriter. Nothing works.
Is there anything more I can do?
Thanks for this great project! :-)