Sometimes crafting rope from vine will create "fake" rope, and won't actually consume any vine, and the resulting rope will not be usable anywhere, and will disappear after a reload.
I have absolutely no idea what causes it, it works fine for hours, and then suddenly it does not. It also messes up the crafting grid, and leaves "phantom vine" in the grid, so other recipes will think there's a random piece of vine in there somewhere, even thought it's invisible.
I've seen people on reddit complain about not being able to use the crafting grid twice already, I ask if they made rope recently, and they did.
Basically this:
https://www.reddit.com/r/VintageStory/comments/1tgqaqk/comment/omi3o6u/?context=3
https://www.reddit.com/r/VintageStory/comments/1sue7az/comment/oi0kpub/?context=3
EDIT: while I do use mods, some people commented that they are playing full vanilla, and still had the bug.