Ok, so I wanted to create a whittle-down goal, went through the help section, and was horribly confused.
At no point in the goal creation process does it ask for a rate or end date. So after making it I got a road with slope zero.
Then I tried to change the slope/end date with the road editor on the goal page and ran into a very weird bug where a date showed up in the “end value” field, and it wouldn’t let me update. I had to delete that line.
All in all, the process of creating a whittle-down goal is incredibly confusing and clear, and the help docs don’t provide much help.
I also want to report that this “rate cannot be 0” bug is still there - I also experienced this during the process of goal creation after hitting the “back” button.