Unable to render Card preview


I have submitted a number of url for Twitter summary card validation and I keep receiving the “Unable to render Card preview” error. Any ideas as to why?

Here are a few of the url’s submitted:




I should add that there is no log error either. Here is the meta data that is from the first link:

I’ve tried many plugins for Twitter cards and none seem to work, although this one seems to work fine on another site of mine.

Any help would really be appreciated!