For all still having this problem and as for me none of the posted solutions worked out.
I've had the similar issue. The image was showing correctly in all other share dialogs. Only WhatsApp couldnt display the image, even though the facebook debugger has the og:image tag correctly.
The solution that worked for me: I am using firebase. For uploaded content in their storage, you get a unique Download URL with a media token. Something like:
https://firebasestorage.googleapis.com/v0/b/XXXX.XXXXXXX.com/?alt=media&token=YYYYYYYY-YYYYYYYYYY-YYYYYYYYYYYYY
I used this URL in the og:image meta tag. It worked for Facebook etc., but it seems like WhatsApp couldnt download the image from this URL. Instead you need to include the image in your project directory and use this link for the og:image tag. Now it works properly in WhatsApp too.
Before (not working in WhatsApp, but facebook etc.)
<meta property="og:image" itemprop="image" content="https://firebasestorage.googleapis.com/v0/b/XXXX.XXXXXXX.com/your_image?alt=media&token=YYYYYYYY-YYYYYYYYYY-YYYYYYYYYYYYY">
After (now working in all shared dialogs tested, including WhatsApp)
<meta property="og:image" itemprop="image" content="https://domain_name/path_to_image">
Hope it might help some of you :)