Just made a duel and after that I couldn't load or save. The options were grayed.
That only resolved after quitting and restarting. (terminating fold.it and only restarting doesn't work, thats what I first tried to not lose my solution with quit+autosave)
Today i had the same Issue. I played the Grand Challenge 9 and my Score wasn't the at very Best, i was in the middle of doing some changes. Then started a Duel. After the Duel (which I lost) i couldn't load the Very Best State anymore. hitting the Ctrl-B or the A-Buttons only brought me back to where i've been when i started the Duel.
I forget to mention the score buttons and shortcuts.
btw: We were duelling each other if this has any meaning.
Thanks for the heads up, the bug has been fixed and will be pushed out in the next update