While collecting logs I noticed that a stack that was nearing the 1k mark went from 998kg to 0k kg, then to 1k kg with some starting a new stack. I split off 1kg of wood from the stack and it showed 999kg, but when I split off anywhere between 1gr (0.001kg) and 999gr (0.999kg) it showed 0k kg.
I checked for this bug on other resources as well and couldn't find a 1k stack that didn't show this behavior when less than 1kg was split from it.