Yep! I found the request bug! Or at least for me...

If I alternate between folders when I request artworks, I can request more than 10 artworks in my group! If I request 10 artworks in the same folder, then I'm stuck with the red-message-of-group-death and can no longer request artworks in any folder! Guess that if I stick with 9 artworks in each folder, I can request of bucket load of art! 

I've sent my findings to the Help Desk and hopefully, they'll be able to fix this!