When Boudewijn cuts into my dances and I click to challenge him, it takes me directly to a blank page. Its done this twice. Well, three times if you count the first time it took me to an error page.
-Blank duel pages -Error "NPC not asked you to dance" when you click on the duel option -Being taken to the dance forums instead of to the proper page though this may be from clicking the wrong button
A work-around, special thanks to users Yoshi and Zay for this
upon reaching the blank duel page after challenging him, replace the address with one of these links:
http://subeta.net/explore/masquerade.php?act=duel&choice=1
http://subeta.net/explore/masquerade.php?act=duel&choice=2
http://subeta.net/explore/masquerade.php?act=duel&choice=3
Which choices are what weapons if there is a certain method you want to try: 1 - rapier 2 - dagger 3 - flatsword
To move on to the next page replace the numbers at the end of the address to 1,2, or 3, then hit enter. Repeat until either you receive an achievement or you hit the "NPC has not asked you to dance" or an error page. Yes, your pages may still be blank while doing this. Mine were but I still managed to get both achievements this way. Be sure to check your inventory to look for the bag of trinkets if you won. I really hope this work-around works for you until this issue is fixed!
ASLO If you are using ANY type of custom CSS, this may help you out:
I am getting the exact same thing. Yay! an event bug and achievements I'll never be able to get; v;
Some things - Using the latest version of Firefox. NOT REFRESHING on the dance floor pages. This happened for accepting dances and having dances accepted by other people. Not opening multiple dance floor pages.
Edit Another challenge, another blank page. I'm going to wait a bit before accepting dances and clearing events until this is looked into.
I'm having this issue and I am using Safari on a Mac
[tot=superferretlover]
July group!
I just wanted to let you guys know that I have reported this :)
Dexter by ❤
Thanks! If you need anymore details on our ends let us know.
I will add this to the report
Dexter by ❤
Still blank, the second time for me now :(
[Kiss=Trubble] [Flower=Trubble] [ToT=Trubble]
Yeah just happened to me too, I've been dancing since both before and after the addition of him being able to cut in was mentioned in the news and this is the first time he's shown up for me and yet it seems he's escaped the duel.

Well it finally worked, good luck to everyone stuck
[Kiss=Trubble] [Flower=Trubble] [ToT=Trubble]
I'm getting blank using google chrome every time he pops up. Getting frustrating.

I have clicked on the red button each time. It takes to the duel page (with duel in the address) but the page is blank other than the header and the contact us links. I'm not using custom css.
When will this be fixed? I just got my second duel, but another BLANK page has popped up, and it does not want to reload (it stops after a second or two).
[tot=superferretlover]
July group!
I have gotten another blank page too. I just went ahead and accepted my friends' dances so they won't stay in limbo.
Five duels missed because of this bug.
You got a forum point while making a post! Um... thanks?
I've gotten the event three times. The first two, when I clicked to challenge him, it immediately said "Oh No! [NPC] Gossip Boudewijn hasn't asked you to dance!" The third time, it took me to the page where I choose a weapon, and when I clicked one of them I got the error again. :(