Problem with Crosserville Clues: "No dupes found"

[John R. Conrad]

I am a relative newcomer to Crosserville, but previously used Crossword Constructor and have published eight crosswords in the NY Times Crosswords.

My problem is this: All of sudden, when I asked to "Check for dupes" in a fully clued 21x21 it says "No dupes found" but there are many dupes there. It is doing this even with older puzzles, that previously showed dupes fine. I have tried clearing caches and history, rebooting, etc. Any ideas?