Social image not showing up when pasting the page's link into a message on LinkedIn. "No alt text provided for this image."

I would appreciate help troubleshooting a problem of the social image not showing up when pasting the page's link into a message on LinkedIn. (It does behave correctly in an iMessage) The image either shows as missing, or in Chrome says "No alt text provided for this image." (alt text doesn't seem to be an option for these images anyway)

I have determined that it's working on a page that uses the default social sharing logo, but after removing the alternate social sharing image from this page that image didn't show up either.

This is the problematic page: https://www.2020mom.org/2021-annual-forum

This is a page without a specific image assigned, that is populating an image correctly: https://www.2020mom.org/individuals

Any insight would be appreciated.