Well, if you happened to click in the link in Claire’s earlier post, then that would have launched the game in one-color mode and would explain everything that you saw. You would have seen an initially empty board, since it takes about a second for the purple hints to pop-up, and if you make a move before then, you navigate away from seeing those hints (since they are only put in the root node). Hence, after your first guess and returning to root, you would see all of those hints for the first time.
I am to reproduce your observations by starting the one-color mode of the game. However, I have not been able to reproduce the bug outside of starting it with one-color mode.
If you wish to further confirm what might have happened, you might be able to check your browser history to see what URL you visited earlier. However, without further information, I cannot confirm if there is actually a bug.
Note: I’ve Claire’s previous post mentioned above in order make it clear that that link modifies the game to provide all purple hints to start.