I worked it out. My bad
- I had an upgraded setup
- that meant I had the old style 20 day search one route search box as well as as the 20 day search multi-city
- my errors only came up in the old style search box

A Nightly update that failed caused me to reinstall and the old style search box is no longer displayed. The new search box can do the 20 day search correctly.

Thanks!