Hi Victor,
Thanks for the assistance.
I’ve enabled the debug log, there’s only one error, but this seems to be thrown on every page load, not just when updating an event, so I believe it’s unrelated.
The problem does not happen when creating an event, a new event saves OK. The issue seems to happen when adding a new ticket type to an existing Event.
I’m able to create a new event with multiple ticket types, but adding a new ticket type to an existing event seems to cause the issue.
I am going to check with our external content provider on being able to update WordPress, once I get that confirmation, I’ll upgrade and try testing again.