I've had issues off and on with previews when sharing Zenfolio images on Facebook for some time (and only ZF), usually fixed by using the fb debugger. However, even that doesn't work anymore. I scrape, re-scrape, reload, etc, with inconsistent results, regardless of how old the gallery and/or image is. I'm getting a new error from Facebook now though: fb:app_id hasn't been included in the meta tags. Specify the app ID so that stories shared to Facebook will be properly attributed to the app. Alternatively, app_id can be set in url when open the share dialog. Otherwise, the default app id( xxxxxxxxxxx ) will be assigned.
...and nothing shows.
I'm hoping this helps ZF figure things out once and for all (assuming and hoping they care)