Sometimes when you share a URL in Facebook you notice that there is no description or thumbnail image in the shared link. This happens mostly because there is no image and/or description in the URL you are trying to share. In order to find out what is missing from the URL’s contents that causes this issue, you can use Facebook’s Sharing Debugger Tool.
Here is the link to Facebook Sharing Debugger Tool:
Just copy and paste the URL to the edit box shown below and press Debug. Wait for a few moments for Facebook to load the URL and detect the issues. If you are sure that there is no problem with the URL anymore then press Scrape Again so that Facebook tries again to load the URL. If it is being displayed as it should, then you can go ahead and try sharing the URL again.
Below is an screenshot of Sharing Debugger: