It appears to work fine on this forum. What version of NodeBB? What do you mean when you say it disappears? Can you record your screen?
why nodebb use gravatar image for og:image
and how to fix it
@PitaJ thank to reply
but I already set og image
and where to set thumb image
@Krissanawat-Kaewsanmuang you misunderstand, that's just a reference of the code which by default falls back to the user image if there's no topic image.