Hallo Richard
Thanks for using our plugins and welcome to the forums!
I’m sorry you are having an issue here, let me try to help you with this.
I checked the system information you shared. In that I see that you have a fresh version of The Events Calendar, but the other the calendar plugins seem outdated. So as a first step it would be great if you could update at least your calendar plugins to the latest versions. (Using older and newer versions together can cause glitches and errors.)
It is also recommended to make a full backup of your site and your database before doing any major updates, just in case something goes wrong.
Could you share with me more details about what is happening? Does it still happen after you updated the plugins? Can You reproduce the issue? Which event / ticket is the user buying? What is the result?
The more info, details, screenshots you can give me, the better.
Thanks and I’m looking forward to helping you with this.
Cheers,
Andras