Thank you for your question.
Are you using any image lazy loading method on your site?
If yes then please disable it as I think it is causing this issue.
If not then would you mind if i log in to your site and do some troubleshooting? If this is ok then could you please share me your site log in details privately by adding them in the box having text “Click here to share private content. Only you and forum moderators will be able see it.”?