The reason this happens is due to Facebook/Linkedin caching everything. This means that Facebook or LinkedIn won't immediately pick up your changes.
So, what's the solution?
Use the Facebook Debugger to clear Facebook's cache. This is how Facebook sees your link!
If you go to the debugger and drop in the URL you’re having trouble with, Facebook will actually reach out to your URL right then and grab the current content to display the debugger results. Doing this also clears Facebook’s cache of your page instantly. (sometimes you need to do it 2–3 times to get the latest updates.)
After you link your URL, you can immediately go back and type your update in again, and the good stuff will show up. It’s that easy!
Still not working and having a custom domain?
If you are working with a custom domain, and Facebook is not recognizing your content, it is most likely because you have connected your domain incorrectly. You probably forward yourdomain.com to strikingly.com/yoursite.
Clearing LinkedIn’s Link Sharing Preview Cache
1. Access the LinkedIn Post Inspector here. If the link doesn't work, copy this URL to your browser: https://www.linkedin.com/post-inspector/inspect/
2. Input your site URL and click the "Inspect" button. The updated share image will be shown on the preview.
3. Try sharing your URL again on LinkedIn to see if it is updated.
In case the post inspector doesn't work, you may clear the sharing preview cache by tricking LinkedIn into "thinking" that your page is a brand new page. You can do this by adding an invented variable to the link when you share your site on LinkedIn.
Original link: http://www.domain.com/
"New" link: http://www.domain.com/?1
"?1" was added at the end of the site's URL. It will force the metadata to be recollected. Don't worry, it won't affect your webpage.