I have a post with a featured image (size 736x212). The post url is this. I shared my post on twitter, but the tweet doesn't show the image (if you want to check click here). What could be the problem?
Twitter has some limitations upon file extensions. I see that you're passing on some variables within your meta tag.
URL of image to use in the card. Images must be less than 5MB in size. JPG, PNG, WEBP and GIF formats are supported. Only the first frame of an animated GIF will be used. SVG is not supported.
Try removing the variables within the image url, it could possibly block twitter from thinking it's a valid image. You could also check the filesize of your image.
Checkout Wordpress plugin called SVG Feature Image on GitHub.
This plugin is written to convert the SVG featured images to a socially sharable thumbnail images on the fly via Facebook & Twitter.
This is a newly developed plugin & currently under source code review with Wordpress. Meanwhile checkout the project on GitHub.
It's completely opensource and free.