Well, my cats have conquered it. Lil' Girl knows to immediately life the one end and treats fall out the other side. If, for some reason, she doesn't make that connection right away, Autumn is right there to catch the treasure. So I needed to come up with a new puzzle.
This time, I took two toilet paper rolls and covered them in felt. I then cut holes on either side of the original tube to the size of the toilet paper rolls. With heavy duty thread, I hand-stitched the rolls together:
And thus came up with a new treat dispenser - harder to lift just one side, and difficult to know which side the treats will come out of!
Hopefully, this will keep them stimulated for awhile until I can come up with something else!