Wrong image is displayed on summary card

[recrwplay]

When I run a URL through the validator, the image that I want to be displayed seems to be detected, but it is not the image displayed.

Eg, when the validator detects the following meta for one of my web pages:

The card preview instead displays my fallback image. A tweet for the same web page also displays the fallback image. Why is the image used in twitter:image not being picked up?

Could it be because the site’s robots.txt is blocking twitter?

[rchoi]

Do you have an example URL? Maybe the og image tags are somehow coming into play.

I would also try using twitter:image:src as the tag name.