FAQ: Why is the Overview Still Showing Incomplete Sections?
When you have fields that are blank they will lead to a completion % below 100%.
Although the platform assumes blank income and expenses values are zero by default, to get to 100% completion % and to remove that warning you typically need to enter $0's in all blank fields. This is explicitly telling the platform you intend this amount to be $0 versus it potentially being forgotten.
That being said, its not critical that you get to a 100% completion % to move forward with your plan. As long as the data in the Discovery phase is accurate that is the most important thing.