Since the ability to change schemes for a subset of your symbol classes was introduced, it is very easy to accidentally only apply a color scheme to a few of your symbol classes. It's also fairly difficult to correct this since you can't just select all your classes and then re-select the same color scheme - you need to select a different color scheme, click the dropdown again, and reselect the desired color scheme. Please allow the user to re-select the same currently selected color scheme so that it can be applied to a different selection, or perhaps introduce a "apply to selected" button.