Here is the latest: Gallery Card displays OK in Timeline.
In Search results it is replaced by Summary Card without any thumbnails. So just the description is left. But if I click through the time stamp to Status View I see it as Gallery Card again.
Comment: when URL with Gallery Card markup is tweeted for the first time, thumbnail images get cached and there’s no way to change a thumbnail after that. It’s not clear how long this cache lasts (it’s not 24 hours or something needs to trigger re-cache, see https://dev.twitter.com/discussions/16318).
Thanks