Some weird Collobora editing issues

Nextcloud version: 16.0.5
Operating system and version: Ubuntu 18.04
Nginx: 1.14.0
PHP version: 7.3.9
Collabora Online 3.4.2

If I create a New Document or New Presentation everything works fine.
If I create a New Spreadsheet I get this message:


Although you cannot make any changes when you exit the file it has been created. If you now try to edit it you can.

Here is a snippet from the log file:

Thanks for any help or ideas you can give me.