Sophisticated backpack contains pouch, double pouch, belts, small backpack, big backpack. Your mod is very satisfying. Sophisticated backpack is used in Big modpack like Vault Hunters and i would really like smooth swapping to be integrated with sophisticated backpack if its possible. Vault hunters runs on version 1.18.2 and it is planned to soon port in either 1.20 or 1.21.

+1 I'm having the same issue, I'd love to be able to use the two mods together.

+1 same issue

+1 same issue. I'd like to compare crash reports with others having the same issue. It seems to not have been fixed for years. My crash report references Index out of bounds, and on the surface that sounds like a simple enough fix.