NC 25 - Office document loading - stuck

Greetings,
I installed NC 25.0.2 on Ubuntu server 22.04 as SNAP + SSL certificate from Let’s encrypt - VPS server 2 CPUs + 4 GB RAM

Installation was successful.

I chose to install default apps during installation.
But when I try to open/create some Office document (Word or Excel) there is some problem because I see only a black screen with white text → Document test.odt is loading.

I expect that document would be open but that is all. No progress to load the Office web interface.

When Nextcloud office administration settings are opened there is a green dot - I see that the Collabora server is used and working.

What should I do to fix it?