Good evening Ken and welcome to the Events Calendar Support forum!
Thank you for reaching out to us.
We are sorry to hear about the difficulties you are experiencing while trying to get the QR check-in to work on your installation. I would love to help you with this topic.
As a first troubleshooting step, could you please provide us with your complete system information in a private reply using the instructions found in the following link?
https://theeventscalendar.com/knowledgebase/sharing-sys-info/
Secondly, could you tell me what is the user role of the WordPress user you are testing with ?
For the QR check-in to work correctly, this user needs to have Edit Post capabilities.
Hang in there!
Geoff B.