@margaret.birch I am going to echo Andrea's comments here. It is tough to walk this line. I tell students I am not their "teacher" during the 8 hours of the task, I am a "proctor" which means there are certain things I can and cannot do. I also use Andrea's technique when students ask me questions. I take out my rubric and I literally read the rubric to them in the form of a question.
I have heard of some teachers putting a sign on their door saying "testing in process" to really drive home to students that they are taking the test during this time period. That might be something to think about for the create task.
Also, I would keep track of what things you are seeing this year so you can consider how to prep students next year too. I know I always think that I will remember what students struggled with, but I always forget. I started keeping a blog this year with just notes from each day so I can look through them next year a bit.
It is so tough to put on the "proctor hat" when as a teacher you are used to providing students with pathways to be successful, but unfortunately that is a bit of the AP game. Also, students might surprise you - once they realize you cannot answer their questions, you might be surprised by how resourceful they can be. It sounds like your students are really motivated - nice work!