I have 10 workspaces in Opera and I close opera daily. When I start Opera again the next day, all tabs in a workspace are occasionally closed every few days. The workspace is available, but all tabs in it are closed. It doesn't always affect the same workspace, but changes randomly. The first workspace 1 seems never to be affected.
Since the open tabs are important to me, I definitely want my tabs to always stay open and be opened again after a restart.