Thanks for writing to us. Please let us know which platform you are using. When did you start experiencing this issue? Is this happening with all projects or just a particular one? Do you get any message popups while opening/ closing the project or Adobe Express App?
Meanwhile, if you're working on any browser, try after clearing the cache/cookies and restarting it. You may also try using a different browser or incognito/private mode.
If you're on any mobile device, please ensure that the device OS and the Adobe Express app are up to date.
If the issue persists, let us know about your observations, and if possible, please share with us its screen recording to investigate further?