We just posted justknimeit KNinja @MartinDDDD’s solution to his own proposed challenge on invoice processing! 
This challenge was notably hard and combined several aspects of real-world data analysis for finance. Our community did not shy away from it, with some folks even mentioning that this was, so far, the best challenge of season 4! 
The required skills revolved mostly around data visualization, data wrangling, and reporting, but the complexity of the data and the tasks themselves made this puzzle difficult.
Tomorrow we are giving everybody a bit of a Summer break with an easy challenge on PC games! See you at the KNIME Forum? 