owncloud does not open at start

Although I have clicked on “start at registration” in the settings, owncloud does not start always when I start the computer. This happens on a Mac Studio and also on a MacBook Air. I think it happens when I restart the computer (or after a MacOS update). As this happens quite often (e.g. every 3 days), this is really annoying, as I never know whether the files have been uploaded or not.