Each Task List can have a theme, which changes the colors of the Tasks for that list. For example I have my personal lists set to blue and my work lists set to red. Before I updated to 2.77 today (or at least very recently), these colors would persist to My Day. This would allow me to easily see the general type of a Task according to the color of the Task completion circle. This is no longer happening, in My Day all tasks are blue. All the Task Lists themes are still correct.