Hello.
I reported this bug on the repository of Ilshidur, and he told me to report it here.
I'm a Mac user. I've tried to use your application a couple of times in the last 2 months, but it seems like it doesn't work. Because i'm a computer scientists myself, i've done some further analysis in order to track down the problem. Apparently, the item sets are placed in the wrong directory of the League of Legends.app file...
I'll report here what I found out.
Your application places the item sets (sub-categorizied in folders, one for each champion) in this directory:
/Applications/League of Legends.app/Contents/LoL/Config/ItemSets/CHAMPNAME/ITEMSETNAME.json
But, in order to make it work, the correct location should be:
/Applications/League of Legends.app/Contents/LoL/Config/Champions/CHAMPNAME/Recommended/ITEMSETNAME.json
I hope you found this report useful.
If you need any other information, I'll be happy to collaborate.
Bye.