First and foremost, individual sharing can only work with a unique URL to any given photo in the page. If the lightbox is open and you don't see something like #!jig/ML/9270 in the URL bar, then that's the problem.
- When using prettyPhoto lightbox, go to JIG settings > Lightboxes tab > PrettyPhoto settings > prettyPhoto deeplinking and set it to Smart Deeplinking (recommended) - identify by content ID option.
- Don't forget that the default mobile lightbox is PhotoSwipe 4. So, also check the JIG settings > Lightboxes tab > PhotoSwipe settings > PhotoSwipe 4 Smart Deeplinking setting, maybe you have turned it off. Set it to Automatically decide based on Smart Deeplinking for prettyPhoto which is the default value. It will automatically use whatever you've set up for prettyPhoto. Or you can force-enable it by choosing the Smart Deeplinking - identify by content ID option.
- Proper individual social sharing is either not possible for other lightboxes or not added by JIG's Smart Deeplinking feature, therefore is not covered by support.
- Open the Facebook Debugger.
- Copy the URL of the page with the lightbox open and paste it into the field.
- Click Debug.
- Click Fetch new scrape information.
- Look at the When shared, this is what will be included section, does it look right?
- Click on the preview, does it open the lightbox with the shared image in it?
What to do with the results:
- Check out the warnings. You can usually ignore Mismatch og:url and canonical url message.
- Observe the These are the raw tags that we found and the Based on the raw tags, we constructed the following Open Graph properties section to see how it figured out what to show when shared. Perhaps you can notice a problem.