In Window mode, after closing the print preview, you presumably see the start-up unnamed drawing. But the drawing from print preview is still there.
In the Drawings menu you see a list of open drawings, which should contain the missed drawing.
In Tab mode it is more obvious, as each drawing has its named tab, which you can click to activate the drawing.
This behavior is indeed irritating and there is an open issue on GitHub, but sadly it is not solved yet.
investing less than half an hour into Search function can save hours or days of waiting for a solution