I have been unloading liquids from one container to another, for example, pouring bottles of water into a jerry can. If you are wielding the target container, after you finish a sequence of unloading, you might accidently try to “(U)nload” it, especially if the container is designated “U”. This does not always prompt for a target container, the liquid inside disappears, and does not fall to the ground as if it were dumped out. I’ve done some testing and I can’t reliably reproduce it every time, but it happens quite often.
I’m using the today’s experimental, 0.7.1-166-g6fb9379.