OK, some more info that might provide a clue to the problem I have.
FIRST: I am a layman trying to figure out how to fix this. Apologies for any stupidity –– my knowledge of coding is very limited.
So here’s what I’ve found.
In July 3 Twitter began to deprecate the Photo cards –– exactly the meta I was using: https://dev.twitter.com/cards/types/photo. This was the only type of card that allowed an empty title meta: [meta name=“twitter:title” content=""]. The Photo card is now mapped into a summary card with large image: https://dev.twitter.com/cards/types/summary-large-image. The summary card with large image requires a title and seems not be reacting too well to the empty title meta.
The problem is that Tumblr photos do not allow a title. They have a caption and that’s it.
Could anyone here confirm this is correct and if a solution is planned for this?
Many thanks.