I found a solution and want to share it for everybody who is facing the same issue.
In TEC / Settings / Tickets I set it up like this:
“Generate attendee data” = ONLY on status “Processing”
“Send tickets to customers” = ONLY on status “Processing”
Before, I had set several checkmarks there, and the PDF file was not attached.
In my case I use a code snippet to auto complete orders, so this solution is fine for me.
NOW IT WORKS! 🙂
And also: I use the Germanized plugin and deactivated the “prevent cancellation by the customer” setting.
Maybe that has something to do with it, too.
I’m glad that I can give something back to this great forum. 😉
Greetings,
Hannes