Have you used any of the suggestions?
Do you have the path to the image blocked in your robots.txt file?
If you haven't tried them yet, maybe the "troubleshooting" can help? https://developer.twitter.com/en/docs/tweets/optimize-with-cards/guides/troubleshooting-cards
Is it possible that may be Twitter has disallowed taking external URL????
You seem to be missing the twitter site tag which hold the twitter username you want to link to:-
<meta name="twitter:site" content="@MyNameOnTwitter">