Use mod version 1.6.2

When you open a pouch with something, and then press Q button to throw out the pouch. The Gui of pouch will not disappear, and you can still take the item into your inventory. Then you pick up the pouch you threw out, and the contents are still there.

We'll look into this, thanks. We may only fix it for the 1.18.2 release as I'm not sure if we'll go back to 1.16.5 to fix stuff, we'll see.