Bugged sauerkraut and/or hamburger recipe?

I just wanted to cook 2x hamburgers using:

8x hardtack
2x chunk of meat
2x pickled vegetable
2x sauerkraut

I have a sealed jar of sauerkraut, so I have to open it in order to cook.
Once opened the game shows I have (4) sauerkraut inside my jar.

Ok! Let’s start a 2x batch!

Wait… what?!?

Fortunately I have another sealed jar of sauerkraut (so 8x sauerkraut in total). Let’s open it and see what happens.

well now it works…

Apparently the game sees a 4x sauerkraut jar as a 1x sauerkraut component.

Bug?

Try to unload the jar before you craft