Hello and happy Friday!
I notice in your System Information you have Event Tickets Plus version 4.3.5 installed while the latest version is 4.4.2. It’s recommended staying updated with the latest versions to avoid potential conflict. Please update to version 4.4.2, then review the Testing for conflicts guide and let me know what you find out.
There is also a chance your template overrides are either missing important code or using outdated code. When users have custom templates, they are responsible for updating them to match changes made in new releases – of course, we try to minimize disruption as far as possible. Also, we try to clue them in to things they should look for by providing useful data in Events > Help > Recent Template Changes. If you navigate there, you should see a list of recently updated templates (which changes each release). You might also want to review the Themer’s Guide to ensure everything is saved properly.
I’m unfortunately unable to provide support in this case seeing it’s relative to a theme customization/conflict. Please review our What support is provided for license holders? Knowledgebase article for more information.
Thanks and have a great weekend ahead. Cheers!