May of solved is this time, I'm pretty sure it was to do with the "drag and drop" feature I added in a previous patch.
I also limited the amount of an item the game calculates to improve performance if you tend to have a lot of items in your inventory.
Here's the full patch notes:
- Added crafting limit to 32 items at once.
- Removed inventory "drag and drop" feature.
Changed files in this update