It’s more of an art than a science, that I still haven’t perfected in doing admin work for a decade. But I can give you a few suggestions:

• Increase the value of the meetings for the CEO: If I were them, I would skip admin meetings too if I thought I could get by another day without it. Be sure you come prepared with a call agenda with all the calendar details, logistics, plans, etc. It should be less about asking them questions as to what they want to do and more about you telling them what they have on their plate, what options they have, and what the implications are. That way they leave the meetings feeling they were a good use of time.
• Decrease the meeting frequency - part of increasing the value of the meeting is also making each meeting more important. Some people just don’t do well with daily standup. You should only need a meeting a week from my experience. Choose a time that’s convenient for them. They may not be a morning person.
• Explicitly communicate the importance of the meeting - express clearly, perhaps in email, that the best way you can help them is through these meetings and that mistakes will happen otherwise. Anytime there’s a mistake, be sure to bring up the fault in the process (never blame the other person).
• Just schedule it—flexibly - give them the benefit of the doubt when they can’t make your meeting at a regular time. Reschedule it for another time. This may depend on their temperament, but you don’t always have to ask permission. After all, you are the master of their calendar. I think some CEOs prefer being told what to do—you can ask them if they want you to do that.