Evan,
Do you have content pages as well as question pages? We just updated to 2.5 and one of our instructors was having the same problem. When I went into the settings page and found the Minimum number of questions which was a setting to me and read the information, found that when the lesson has content pages as well as question pages, it needs to be set to zero. Did that and went back in and did the lesson, it worked. MIght check that. Picture included below.
Paula
