Thanks for the bug report, this was a good catch.
We looked into it and I wrote a fix (turned out it was an oversight on my part). We'll patch it in as soon as we can confirm that the fix works.
The scoring rule for Straight Flush and by extension Royal Flush was
"is there a straight and is there a flush"
when it should have been
"is there a straight and is there a flush using the cards that form the straight"