All things considered, this is pretty minor.
The “state breakdown” showing how workers at a building are spending their time seems to be incorrect when wagons are available to do the transporting of goods. The bar graph makes it seem like the workers are spending the vast majority of their time transporting when in fact they are working most of the time.
I made a video to help explain: (18) Farthest Frontier Quick Tip: State Breakdown Bug (Mines/Pits) - YouTube