Learners never see a screen titled Assistant offline or Assistant locked. When they cannot use the assistant, the lock screen title is Access denied, with the text You do not have access to this assistant. Please contact your instructor for assistance.
That screen appears for two reasons: the assistant is not public, or that learner is banned.
The assistant is not public
Turning off Make assistant public in Share takes the assistant offline for learners. The teacher confirmation is This assistant is now offline (or Assistant unpublished).
The learner is banned
On Learners, Ban learner blocks one person. The confirmation says they will no longer have access to this assistant. They get the same Access denied screen. Use Unban learner to restore access.
Timeline gaps are different
On the teacher Timeline tab, a gap between two periods shows Assistant is offline for 1 day or Assistant is offline for X days. There is no Take offline button.
That badge is on the teacher list only. It is not a learner-facing title. The learner lock screen is still Access denied.
Related
For learners: I can't open my assistant
Need help? Write to [email protected].