I wonder if being maxed out is an issue. I've also drawn a blank from mines today, although it's been fine on other days at least on my Android game. All of the rock chopping to keep up with the need for lucky dust makes it hard to keep the numbers below the max - this event is good for the supply of resources to create swords and wisps for the future though!
And I have not harvested any crops for several days - I'm getting all of the skunkupines I need via the rock chopping. I wish I hadn't panicked and used up a couple of traps early on.
Further up on this thread I read that someone had not got a green wisp from Ivy. I also thought this was a guaranteed drop. Otherwise it's going to be difficult to finish. Don't think I'll make it anyway on my second game. I'm too far behind due to being delayed at the start because of not having any mermaid scales and there are so many green wisps still needed.
Also today I've done badly with the gold coins - always hopeful that the adventures will generate a green wisp, but they never seem to.
Edited to say: Just gave 15 silver to the greedy elves, forging two swords and making a royal block, a fancy block and an earth wisp - still got no purple wisp on the mine collection (6 times with no result now) so suspect it's not to do with everything being at the max.