Get in the item editor. Look in the drop-down box with item classes. There are 20 Custom Item Classes not in the correct numerical order of some part.
From top to bottom, it's:
1, 11, 12, 13, 14, 15, 16, 17, 18, 19, 2, 20, 3, 4, 5, 6, 7, 8, 9.
Custom Item Class number order incorrect [679]
Well yes, like all item classes they are sorted alphabetically by name :shrug:
Came in too late, before the edit of post #1.
The only way to fix that is for a one-digit number be followed by a 0.
01, 02, 03, 04, 05........
But if you feel like you don't want to do this, move it over to exterminated anyway (or limbo it).
or not sort by binary >.>