Attention, this issue applies to those who downloaded AJG: Advanced Items before the first of February, 2021. 

During compiling, the options file was kept with my own Windows username, which prevents correct generation. Here's how to fix it:

1. Open settings

2) Delete "blitz"

3) Re-open AJG: Advanced Items. The username should've changed to your own one already and AJG should work as intended!

The .zip file currently uploaded on itch.io has the correct options.json now, so you can simply update alternatively.