I tried using Ubuntu 20.04 and 21.10, both have the same situation: after loading a new project (both with and without initial filling), the Viewport tab is always empty, what objects didn’t transfer to it and what light sources didn’t create.
If I install the program on Windows 10, then the standard initial content appears in the Viewport tab and everything works.
What additionally libraries needs to be installed in Ubuntu for the program to start working correctly?