hey, we talked about this via email, so when using Yoast, you need to set the front page additionally in Settings > Reading.
If you don't, then Yoast does not pick up what page your front page actually is, because it doesn't know Lay Theme's custom front page settings, so it doesn't return the right image on the front page
There's also an info box that includes the description about that in the plugins.
However, with the new update, at least an image will be returned. The one that is set in Lay Options will be the fallback image.