I have noticed this on several design puzzles over the past several months: wiggle all with bands will suddenly not work (the protein doesn't move; the score doesn't change). This is true even if I am trying to pull the ligand through empty space (not in violation of its constraints) or to pull it directly out from the larger protein: http://fold.it/portal/files/chatimg/irc_341210_1335589536.png
Changing the bands to strength 10 makes it move but deforms the ligand in the process. On 549, strength 9 or 10 worked but not 8 or less. This happens in the beginning of the puzzle when the protein is not yet in an optimized position and is not yet stiff.
OS: Win 7 home premium