Sorry to hear that @jianwen. Can you restart this computer and let me know if you're still seeing this please?
If you do, would it be OK to reach out to your Dropbox associated email address?
As @Здравко mentioned, based on your last screenshot it appears that you are running a beta (or experimental) build of the Dropbox desktop application and since these builds are still in the testing process, you could experience some issues or an inconsistent experience.
As a first step to isolate the issue, I'd like you to install our latest stable version of the Dropbox desktop application.
To do this, you will first need to follow these steps to verify that you have opted out of "Include me in early releases" option in your settings on Dropbox.com. This will ensure that the application does not automatically update to the beta build after you install the latest stable build:
Then, use the following link to install the latest stable version of the Dropbox desktop application:
Once you install the stable build, it might take some time to re-index the files and sync any pending changes but things should return to normal.
Let me know the results!
PS: I removed your email address from your post for security reasons. If you'd like to reach out to our Support team through email you can do so from the following page:
Feel free to do so @jianwen!
If there's anything else we can assist with, do let us know; we're just a post away.
Have a lovely weekend!
The way we work is changing. Share and discover new ways to work smarter with Dropbox in our community.Sound good? Let's get started.
For more info on available support options, see this article.
If you found the answer to your question, please 'like' the post to say thanks to the user!