We have a site which - due to being an alcohol brand - sits behind an age-gate. The age gate places a cookie onto the visitors computer which is tested against on subsequent visits to check for age approval. This cookie expires after 24 hours - part of our corporate responsibility regarding alcohol consumption and age approval.
With this in place, it appears that the Twitter systems which scape meta-data to show cards (summary, large summary) cannot get beyond our age-gate.
It would be great to understand if this is expected behaviour. Obviously we cannot expose the deeper pages beyond the age gate without interaction with the form on the age gate as this would defeat its purpose in the first place.
Ideally Twitter would understand the age-gate and perform the approval - but this might be expecting too much.
Visit https://www.penfolds.com for the home page
Visit https://www.pendolds.com/age-verfication for a permalink to the age gate
Visit view-source:https://www.penfolds.com/heritage-and-winemaking/the-story-of-grange for an example of a page behind the age gate