Windows 7 x64 SP1
I set up a new category as such:
I double-click a NZB file in the OS, so it gets added in the "Default" category.
I open the browser and change the category from "Default" to "dontunpack".
The category is updated, but the "Processing" is not - it remains "+Delete" instead of "+Repair", like so:
And hence, it get unpacked!
Thank you for fixing!