If a resource gain per second shifts to 0. (ie, you were producing -1 resource per second, get a building to increase it to 0) the layout ps will show the last value instead of removing the per second value.
Updating the page or loading the save from the menu correctly updates the layout and does not show the per second value.
Edit: Actually the issue only happens when going from negative to 0. Going from positive to 0 the per second value correctly gets updated.