can't get image on home page

Try running the url through the Facebook debugger: https://developers.facebook.com/tools/debug

Sometimes Facebook caches old images.

that worked! thank you

Thank you @amduffy! You can also add a meaningless parameter to the end of the url like https://domains.com/my-post-title/?a=1
This tricks facebook into thinking it is another page, but wont affect the appearance on the timeline/newsfeed.