Good evening and welcome to the Events Calendar Support forum!
Thank you for reaching out to us.
We are sorry to hear about the attendee info not appearing on one of your site for WooCommerce-based tickets.
I would love to help you with this topic.
As a first troubleshooting step, could you please provide us with your complete system information for that specific website in a private reply using the instructions found in the following link?
https://theeventscalendar.com/knowledgebase/sharing-sys-info/
Secondly, can you tell me if this holds true both for existing WooCommerce tickets AND new ones ?
Finally, try temporarily reverting back to a default WordPress theme such as twenty-sixteen to see if the issue persists (while having a maintenance page plugin activated).
Let me know how that goes.
Best regards,
Geoff B.