Just FYI- all the links to start new challenges are busted, they all give the same message that 'this player has reached the max of 15 friends helping' only after refreshing a bunch of times, they are just freezing most times.
it is possible that those players did receive the max of help, those go fast , keep trying ,if they are even 5 to 10 minutes old they may be maxed already
When Kano does these multiple calenders sometimes the links do not go dead on some players. Look at the amount of individuals joining the challenges and see if there loaded. If not then Linda or myself can send a message into support. But still needs to be reported again if the links are not going dead after the max is reached on players.