There's no recipe to create an empty canteen anymore. The item appears in JEI as "Canteen" rather than "Empty Canteen" (from my last functional mod setup) and when viewed only shows enchantment recipes. No crafting recipe shown by JEI and attempting to craft with leather gives no results.

Tested both in a full modded setup and without any other mods.

Versions: Forge-14.23.5.2768, ToughAsNails-1.12.2-3.1.0.132
Last seen working: Forge-14.23.4.2739, ToughAsNails-1.12.2-3.1.0.115

Oops. Fixed.

Also, I just renamed the "Empty Canteen" to "Canteen," so don't worry about that