Help with Kitchen Sink Scheme

I've had Worms 4 on my PC for a few weeks now and have been playing like crazy. I've got the time record on all 25 missions, same with the challenges, done the training, modded my weapons to get every trophy, gotten all five easter eggs, bought every available item, and now the item shop just says "awaiting new stock". I'd like to get the kitchen sink scheme but it won't come up and from what I've read I have fulfilled all the requirements. Does anyone know or have any ideas about what the problem is? Maybe because I modded my weapons? Do I need all the coins to purchase it before it becomes available (I only have around 1500 right now)?

Did you unlock all the character sets?

Yes I've bought everything available. Frankenstein, professor, alien, dinosaur, and cyborg sets