I changed the file to one that has green header rows that persist to the next page.
- I followed your directions and got another blank green row
- I select the new row, change the Color and Fill in the Table Designer, click Apply and ... No change
- I select both green header rows, change the Color and Fill in the Table Designer, click Apply and ... No change
This is the file with the real header rows
https://www.dropbox.com/s/f3fj5yttxyv0qla/Section4-Change%20Requests.fm?dl=0
It is a header row--that's good.
It does have manual (custom) formatting.
I removed the custom formatting and updated the style to work properly.
Step one: select header row and set color/shading to table; style settings are set to none, so color disappears

Step two: update the table style as desired:

