Eric, you can view/edit the Change Schedule by going to System UI\Timeline Pages and in there you will see a record called Change Schedule.   If you scroll down to the related lists you will see one where the condition is "Outside maintenance schedule is true" and it will show the changes in Crimson color.

To troubleshoot this, I would suggest going to your change list and filter for changes where "Outside maintenance schedule" is true.

If you have some where that is set to true, verify the planned start and planned end dates to the span of time you are viewing in your change schedule.   In my demo instance one that is "outside maintenance schedule" shows up in the crimson color.