Can't change color palette in Theme Park

[doseas]

Just received 1.0.9.57 update to Theme Park.  The release notes state "Ability to change Color Palette" colors and I can see this in the hamburger menu, but it appears to be greyed out everywhere.  What am I missing?

[doseas · Accepted solution]

Update:  feature only appears to work if default theme is currently applied.  It appears to be unavailable if you are already using a custom theme.