Do CDC class 3 students need to book 3A lessons

Currently doing class 3 license in CDC school, but I have a question. Recently, after completing a few lessons, I saw in the app that booking Class 3A lessons was now an option. But then when u tried to book, it says don't need to book and it stopped me from booking them. I thought class 3 students still needed at least 1 3a lesson to complete the course, but now I'm wondering if we don't. Anyone else faced the same issue?