Hi Rolf,
Thanks so much for reaching out!
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/
To edit the ticket email, I’d recommend starting off by taking a look at our Themer’s Guide, which can show you which templates can be edited and copied in order to achieve the results that you are looking for.
To safely modify the ticket email I would recommend you to make a copy of event-tickets/src/views/tickets/email.php and place that copy in [your-theme]/tribe-events/tickets/email.php
Open the file you just copied to your theme’s directory and modify lines you want.
Let me know how that goes!
Thanks,
Jaime