PC - Microsoft Store Version.
When upgrading from lv.1 Solar panel to lv.2 (high density) the building disappears and becomes uninteractable until you reload the world. This also happened with a food storage silo.
This bug also seems to make the game unable to save during save & quit, but doing a force save, and then ending the application does save the progress (and on re-opening the save file, the buildings have upgraded, are visible and interactable again.)
Lelebees