Please check it as follows:
1. Check if your pictures meet the upload requirements.
2. Check file sizes and dimensions. Make sure the file is less than 10MB.
3. Update your browser to the latest version.
4. Reduce the number of open tabs in the browser you are using.
5. Refresh your Internet connection. You can also try to connect to an alternative network.
6. Clear browser history or cache. Accumulated cookies may cause problems.