Custom Welcome Mail with special characters

Dear community

I am using Nextcloud version 22.2.2. I have customized the mail for welcoming new users like stated in the Nextcloud docs (

I managed to change the logos, buttons and the text. Everything is fine now except for one thing:
The mail should be bilangual (English and German). The problem now is that as soon as I put the German special characters (ä ö ü …) into the email body, the whole text is shown blank.

The charset on the template is set to UTF-8. I have also tried to change the default language to German, which did not help.

Do you have any ideas for me?

Thank you in advance!