There is an error in the Bible in 90 Days reading plan. Day 72 ends with Mark 15:20, but Day 73 begins incorrectly with Matthew 15:21 instead of Mark 15:21. No wonder I was having such a hard time getting past Day 73, and feeling like I was retracing my steps! 
Bob
Could you give me your reproduction steps? I'm not sure what I'm looking for quite yet. Are you using the Courses tool?
It's one of the predefined reading plan documents.