Hey Sylvia, thanks for the post. This is not intended behavior so I'm sorry you're experiencing trouble while using Lucidchart. Can you try opening the document in a Chrome Incognito browsing session? This often improves performance by starting a fresh cookie session and disabling your extensions. It's also worth noting that saving issues are often related to an unstable internet connection. You many want to look at your internet connection to confirm that this is not a factor.
Please let me if the issue persists.